David
Ruether's article On Checking Lens/Film-Plane Parallelism
Related Links:
Lens Test Charts and Instructions
Pentax Lens
Resolution (click lens then lens resolution links)
Bob Atkin's Doing
Your Own Lens Testing
How to test your
lens (William E. Sadler)
How to Buy a Hasselblad by Lance Karp,
Mr500CM
Second Time
Around - Buying Used Gear Guide by David Howard
Abstracted Articles:
Marty Forster's List of Camera Breakdown...
Zemaitis' Checklist Before Buying
Quick Zoom Checks
Body Focus Test
How to Test a Lens
Buy a Used Lens With Confidence
Postings:
Cyber Ghost's posting on Testing New Equipment
Jeff Span's posting on Lens Testing
John Wall's Photo
FAQ listing of Lens Testing Resources Online
Camera
Repair FAQ
What to
look for in a new/used camera
Doing You Own Lens
Tests
Shutter
Testing
Lens Testing Chart and How-to-use Info (2/1/98)
Lens
Tips/Choosing
Manual Camera
Budget Buys (added Sept 1999)
| Related Photography and Camera Testing Links |
|---|
| Top Ten Myths of Photography (Robert Monaghan) |
| Tamron/Bronica's How to Buy a Lens Guide |
| Cleaning a Camera by Philip Greenspun |
| What to look for when buying a (Used) Rolleiflex by Harry Fleenor |
| Robert Atkin's Lens Testing Methodology |
| Where to get Test Targets |
| USAF test chart on CD |
| Testing Super Tele Lens |
| First Attempt at Lens Testing - It's Tricky! |
|
David
Ruether's article On Checking Lens/Film-Plane Parallelism
|
| CALIBRATING YOUR SHUTTERS by Andrew Davidhazy |
| How to buy a Camera Article |
| Testing Bronica ETR lenses by Rick Rieger [10/2000] |
Here are some suggestions on what you can test with a few rolls of slide
film. Slide film is suggested for all the reasons highlighted by Cyber
Ghost in his/her posting below.
Be sure to also review the many issues raised by postings and collected
net-wisdom online.
A common problem in older cameras is focusing problems caused
by deterioration of camera mirror foam (see postings and below). This problem is easier to fix
than lens focusing mount problems.
Derek:
I am a camera tech. for 27 years with high experience on
almost any camera and lenses.
To make sure your nikon lens is working properly,
follow the following instructions.
1- turn focusing ring end to end with constant speed,
if it moves freely with no noise, it is ok.
2- turn f stop ring end to end, it should feel clicking
and no resistance.
3- leave f stop at highest setting (16-22-32 etc.);
the diaphragm should close all the way.
Look from both sides of the lens, the blades should
be clean, with no oil or stain.
4- Actuate diaphragm lever with rapid speed.
Lens aperture must open and close rapidly (no delay).
5- Mount lens on the camera and look at a long distance object
while focusing it. If the image is focused at the infinity
sign of the lens, then it is ok.
Any of the above is correct test for any kind of nikon lens.
jeff
From: "TravGlen" fuzzie@zeus.jersey.net
Newsgroups: rec.photo.equipment.35mm
Subject: Re: nikon lens
Date: Sun, 28 Dec 1997
This is great advice for anyone buying a lens. I would just add that you
should look through the lens from both ends at a bright light, to check for
internal dust, dirt, grime.
[Editor's note: Worry more about fungus or lens element separation around
the edges. A small amount of dust will have minimal impact on image, but
fungus damage is another more serious problem. Lens element
separation can be serious, but is rarely reported in Bronicas.]
From: jf7wex@miyagi.prug.or.jp (SUZUKI Ryuji)
Date: 09 Jan 1998
Newsgroups: rec.photo.equipment.35mm
Subject: Inspecting lenses
In article "lotus" lotus@grin.net writes:
I
bought not one, but two, XA's which later turned out to have mottling on
the rear element, early mold growth caused by leaving the film in the
camera (it is close to the rear element) in a damp area for a long
time. (I
got fooled because the front element looked fine.)
Inspecting lenses in general.
For checking fungus, cloudiness, scratches, deterioration in the
balsam used to cement a group of lens elements, and most of the
damage on photographic optics can be easily found if you look
through the lens to which a flashlight is pointed from the
opposite side. Try various combinations of direction to look and
point the light into.
Of course, make sure you have a small flashlight in your bag when
you look around for a lens. If your car has one and if you drive
to the dealer, you know where you should bring it from.
--
Ryuji Suzuki
s11751rs@UMassD.Edu
North Dartmouth, MA
rec.photo.misc #57641
From: planxan@aol.com (Planxan)
[1] Re: Fog in Lenses?What to do?
Date: Wed Jan 07
Fog does not belong in a lens! You didn't say how many years or what
kind of
camera, but one common thing in very old lenses is fungus. To the naked
eye it
can look like fog - you need magnification to see the filaments. The
fungus
usually grows on the glue used to cement elements together. If this is
the
case you won't fix it - use it "as is" or throw it out if it shows badly.
It
_will_ get worse.
If it's really water vapor, it's probably in-between elements which are not cemented. This would be simple for a knowledgable repairman to fix. An even cheaper fix (if it's water vapor) is to pack the camera in an air-tight back with a dessicant such as good photo supply stores sell (about $10 for a pouch). This stuff is intended as a first aid remedy for a camera that got rained on in a surprise shower. It sucks the moisture out of a camera fine, but the mineral deposits left on glass and mirrors still has to be tended to (at least the metal parts won't corrode). If it's only a tiny amount of moisture, there may not be enough mineral deposits to matter once the water is gone.
From: spirit@nonet.com (Cyber Ghost)
Newsgroups: rec.photo.equipment.35mm
Subject: Testing New Equipment ---- for Newbies! Listen up!
Date: Fri, 26 Dec 1997
Buying a new or second hand camera can be a traumatic time. The
expense, trouble, and the choice is enough to drive one to
distraction.
But one thing any new camera owner should do is test the camera.
Two ways to do this is to use a dummy film, buy the cheapest roll
available and run it through the camera testing all the functions.
Rewind and reload - one might need to use a cheap film extractor to
retrieve the film leader to reload the film. The purpose is to see if
the camera is operating, physically as it should. It might appear to
work empty or at one particular DX setting, switching to auto from M
(manual) often discovers a pup immediately. Many traders set the
camera to M as this produces the best response to auto focus and motor
drive - no waiting for focus confirmation etc, and many cameras will
not use all their functions without the DX information from the film.
Any camera you see set to M is suspect straight away, though it must
be said in defense of traders that this setting also uses the least
power and no trader want to show a camera that goes flat immediately
because it was switched on in the showcase for the last week.
Next buy one roll of SLIDE FILM, otherwise known as transparency
film.
Test all functions of the camera, auto exposure, compensation, flash
dedication, focus - tracking, etc. Do not use all the film on one
subject and use flash as well as available light, never mind the
subject - try to avoid taking actual 'pictures' you want to be
subjective of the camera at this point.
Send the film away and get it back uncut or unmounted. You want to see
what's going on throughout the role.
***UNDER NO CIRCUMSTANCES DO YOU USE A COLOUR NEGATIVE FILM
AND SEND IT TO YOUR LOCAL MINI LAB FOR TESTING PURPOSES!***
Other than testing the actual lab -- it is useless in testing the camera. OK!
MINI LABS WILL;
*Compensate for:
* under or over exposure*
* filters*
* Colour Balance*
* latitude of the film*
Therefore a test film can be badly under exposed and produce useable
prints. Filters will (largely) be ignored so will appear bad value and
of little or no use --( not true as filter are very valuable!)
Colour balance will be adjusted to suit the last film run of the machine.
If you are unlucky enough to be the only Kodak film in a batch of Fuji
then the Fuji filtration is used. Further the operators will judge the
films balance which can be from blue for mauve to red for the same colour.
Mini labs produce negatives to suit their equipment and the faster ones
use the film's latitude to produce flash capable thin negs. If your
equipment is already under exposing then your negs are even thinner and
you might think that you can only shoot in bright light - as film looses
sensitivity the longer it is exposed (and needs more exposure to
compensate) so your Opera or stage shots are totally ruined.
Slide film is not subject to the same variances and so produces the
best set of 'masters' to be referred to for various situations. If
your slides are dark then your camera is UNDER exposing. If light then
the camera IS over exposing. If they are discoloured then the camera
IS leaking light and further evidence should be detected in the slide
border.
Shots taken with filters will show their true worth --- worth one
roll of film to se this alone! And the beautiful sunsets have colours
never before seen. Night shots are unbelievable and available light
can have beautiful orange colours < suitable for some subjects and can
be filtered out with the appropriate filter --and you WILL see the
results.
I am not selling slide film and they are not to every ones taste and
are not the most suitable all round material.
But they show up camera and photographer technique like NOTHING else
will.
If you want to know what your camera is doing, buy one roll of slide
film and really look at the results. If you are testing a new or
second hand piece of kit it is essential.
Buy!
Happy snapping!
What should I look out for in buying a used Bronica classic
camera?
Some vintage cameras get reputations for problems, both deserved and not.
While only a small fraction of users may experience these ''common''
problems, you don't want to be one of them. If your
camera does not have these problems when you buy it, you
may
experience years of
trouble-free happy
ownership with
minimal camera
care.
The last of the
all-mechanical
Bronica camera
line, the S2A,
replaced the
earlier brass
gearing of the S2/C
and S series with a
much more rugged
and reliable steel
gearing. This fact
partially explains
the S2A reputation
for ruggedness, as
well as its being
the last of the
all-mechanical
cameras.
Be sure to
carefully check the
film advance,
especially in the
earlier
pre-S2A cameras.
Shoot some film,
and look for
problems with film
advance
(such as
overlapping
frames). Use a
second film back to
determine if
a film advancing
problem lies in the
body or worn
gearing in the
back. Don't
use TMAX or other
thick film,
according to some
posters (see postings).
The lens focusing
mounts on some of
the early Bronicas
were also problem
points, so if you
are buying an S or
earlier camera,
check this area out
carefully too.
Over time, the
mirror dampening
foam on all cameras
often deteriorates,
although the foam
can be readily
replaced. This
deterioration can
cause
shifts in focusing,
but it may be
readily fixed if
this is the sole
cause. See Replacing
Deteriorating Foam article online. [Ed. note: site down as of
1/2001]
Be sure to check
out X-synch framing
with some strobe
photographs too.
See our X-synch
test page for a
simple way
to test strobe
synchronization
using
glow-in-the-dark
darkroom
tape.
The electronic EC
models used a split
mirror design that
could be very
difficult to get
into and maintain
in precise
alignment (a
particular
problem with
telephoto lens
users). This split
mirror design also
requires a
different bellows
for EC models.
While not a
mechanical or
electrical problem,
availability of
regular
and especially
polaroid backs
and prisms and
similar accessories
can be an issue
with some models.
Finally, you should
read through the Netwisdom
Postings to
learn more about
various cameras,
problems, and
solutions
from other users.
Refer to used
camera purchasing
guides online and
from published
sources
such as Shutterbug
Ads and photography
magazines and
books.
Consider paying a
local camera
repairperson to
check out your
camera too
during a warranty
period or before
buying.
If you need an experienced Bronica repairpersons, see our Bronica Repair Facilities page for a list. Be aware that parts availability is always an issue with older cameras. Moreover, Bronica mechanics are among the most difficult and challenging to repair in photography, so forget about do-it-yourself approaches or inexperienced repairpersons.
Mr. Marty Forscher is a legend in the camera repair field, having honed
his skills in military service and at Professional Cameras Repair in
NYC.
Body focus defects are hard to detect since we view through one optical path while taking picture through another path. Body focus problem occurs when the image in focus on SLR groundglass is not in focus on the film.
Depth of field may mask this problem, but it is most apparent when
shooting closeups or wide open aperture shooting.
Here is a simple test using scotch brand magic tape and a 10x magnifier.
Setup camera on tripod, open camera back, and stretch piece of magic tape
across film guides vertically. Focus on well lighted high contrast object
preferably with dark straight lines.
Look through viewfinder and focus. Use any aids such as waist-level
magnifier or accessory magnifier.
Now look at tape, acting as ground glass, using magnifier. Move lens
focusing ring back and forth. Determine if the most accurate viewfinder
focus point matches that seen with the magnifier and tape.
If it doesn't match, recheck by focusing using magnifier to set precise
focus. Now check through viewfinder. If the viewfinder (e.g., split prism
image) is not in perfect focus, you may have a body focus problem. See
your camera repair person.
SLRs can go out of adjustment, and this test can be performed periodically and especially on newly purchased cameras, new or used.
[Ed. comments: I am not sure that this test is completely accurate,
especially using the vertical alignment approach to position the tape.
On a Bronica, you might check with film insert removed, ground glass
against the inside of the back. But even here, I think this test may be
hard to execute with accuracy.
My personal suggestion is to get the narrowest depth of field possible (closeup, wide open, well lighted subject with crisp lines to focus on). If you have extension tubes, use them to get a very narrow depth of field and sharp focus point. Take photos, being very careful with focusing, using film magnifier. Look at resulting slides or negatives closely with magnifier loupe. Are they sharp? If not, you may have a focusing problem.
Another focusing test I have seen advocated uses a yardstick propped at a
45 degree angle against a wall. With camera on a tripod, focus carefully
at or near the minimum focus distance, aperture wide open. Take a series
of photographs. After each photo, de-focus and refocus, preferably
from both directions on different photos. Examine the slides or negatives
directly (not prints). Is
the target marking on the ruler in sharp focus? If not, is focus point in
front or behind the target marking? Is it consistently in front or behind?
If it is inconsistent, you may have a problem with focusing, a
surprisingly common problem amongst photographers. If the problem is
consistent, you may have a focusing misalignment. If the problem is
the same with different lenses, you would suspect a problem with the
camera body. If only one lens shows the defect, the lens is presumably
at fault.
Another trick from Cora Wright Kennedy's columns in Popular Photography
uses a
pencil in a similar shallow depth-of-field focusing effort. Carefully
focus from a tripod. Mark focus with light pencil scratch. Turn lens to
one side. Focus critically again. Check the pencil mark. Is it centered
or off? If it is off, you may need more practice focusing, rather than
being a camera issue. Try it from both directions.
Another of her tricks is to learn to focus quickly, not slowly, relying
on proper focus to snap out. This trick is especially helpful with
wide angle lenses which are hard to focus. Slowly creeping up on focus point
with
wide angle lens is often harder to properly focus than the quick focus
trick.
Check your eyes. With age, our eyes start to go. Consider getting
adjustable magnifier hood (on Bronicas) or use of eyepiece correction
lenses on other cameras. Some prisms (Nikon HP) are better for eyeglasses
than others, but these same prisms may be worse for non-eyeglass users.]
Shutterbug Ads is the best place to buy used equipment, but how
can you buy a used lens with confidence?
Begin by calling seller, asking about lens condition, known problems, and
what warranty or return privileges are offered.
Start by shooting some pictures with the lens.
Check the lens mechanically.
Look through the lens.
Mr. Shell notes that as a working photographer, he has bought all but one
of his lenses used through Shutterbug Ads and saved
substantially.
[Note: These are very good guidelines, and you can tell that Mr. Shell
was also a noted camera repairperson prior to becoming Editor of
Shutterbug]
| Lens Flare Testing |
|---|
| From Shutterbug Lens Flare Definitions and
Solutions by Don Garbera, p. 38, March 1989 Mount lens on camera on tripod in darkened room and view candle or other small point source of light through lens. Use a multicoated prime lens with low flare levels for comparison. Change f/stops, and move the point of light around in the image area. Besides showing flare, you may also be able to see distortion of the light point into a comet-like tail shape near the edges of the field of view (called coma aberation)... |
[Ed. note: Mr. Zemaitis is a camera repair person with more than 55
years of experience, and still going at it! (see note below)]
[Ed. note: I was pleased to receive the following note regarding Mr.
Zemaitis' continuing involvement!]
Date: Thu, 22 Jul 1999
From: Frank Zemaitis fzemaitis@sabratek.com
Subject: My Dad's camera testing tips
Greetings!
My Dad was pleased to see his camera testing tips posted on your Camera and
Lens Testing Tips page. I would like to point out that he has worked for 55
years in cameras and continues to work (part time). Old habits are hard to
break :^) If you would be so kind and have to time please update the
article.
Thank you,
Frank M. Zemaitis Jr.
(P.S. If you do update the site don't say "was". He still "is" :^)
[Ed. note: got it ;-) I've updated it to reflect his continuing
involvement ;-) Congrats!... bobm]
[Ed. note: A useful test tip from a noted camera repairperson]
Date: Mon, 26 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Cleaning Tessars
The way to tell if the lens has gotten hazy is to open the shutter and
shine a flashlight through the lens. Any haze or other crud in the lens
will become immediately apparent. Also check the finder lens. Haze there
will reduce the contrast of the finder image and make it harder to focus.
Cleaning the finder lens requires actually more disassembly than the taking
lens and will also require re-setting the correlation between finder and
taking lens. The is perhaps better left to a repair type person.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
[Ed. About scratches in glass and coatings:]
Date: Wed, 28 Jan 1998
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Re: German Glass
Peter,
Most optical glass is pretty soft stuff, particularly in comparison with
window glass and such. I don't think the German glass is necessarily any
softer than the Japanese stuff. Coating has a lot to do with it. In
many cases small scratches, which dealers like to call cleaning marks,
really
are not in the glass at all but in the coating. Modern coatings are much
tougher than older ones.
Bob
[Ed. Bob Shell is an experienced camera repairperson and
editor of Shutterbug magazine]
-----
Date: Wed, 28 Jan 1998
From: Mark & Sue Hubbard hubbard@humboldt1.com
Subject: Re: [Rollei] Re: German Glass
Peter,
I experienced the same thing, even to the point that the taking lens on my
old 2.8F Planar would scratch but the viewing lens did not. I agree with
Bob, however, that I think it was the coating that got scratched, and I
never noticed any effect on the pictures I took with that camera.
Mark Hubbard
Eureka CA
----
Date: Fri, 30 Jan 1998
From: Doug Braun dbraun@scdt.intel.com
Subject: [Rollei] More babble on coatings and cleaning
My humble observations:
I think coated lenses are more likely to remain in cood condition
because any damage done by cleaning is very conspicuous, even if
its effect on the image quality is minimal. But uncoated lenses
can basically be ruined by cleaning and still look "shiny". It's
only when you carefully shine light through them and look through
them that you can seen the zillions of tiny cleaning scratches.
I was looking at an older 2.8 in a shop last weekend, and I
noticed that the taking lens had too many cleaning marks to make
it really worth using (especially for the asking price...), but
the viewing lens was basically fine. Obviously the previous
owners were very concerned that that they get the most out of
their fine taking lens by always keeping it clean, and ended up
ruining it in the process. Because they paid less attention to
the taking lens, it survived...
Doug Braun
----
Date: Fri, 30 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] More babble on coatings and cleaning
Taking a pencil flashlight along when buying lenses or cameras is a good
idea. when shined through a lens it will show up any scratches or haziness
right away.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
----
Testing Camera Gasket Seals
Date: Wed, 21 Jan 1998
From: doregan@ibm.net
Reply-To: doregan@ibm.net
Next time you load a fresh roll of film, leave the lens cap on anf cover
the eyepiece and then do a couple of exposures with a bright light
shining on the camera back. Try 1/2 second or longer just to really test
the seals. If the film is not exposed, you're O.K. for now.
Dennis
From: Tony Galt galta@gbms01.uwgb.edu
Newsgroups: rec.photo.equipment.35mm,rec.photo.misc
Subject: Re: Tips for buying used F3 ?
Date: Sat, 17 Jan 1998
One thing that I have noticed on many used F3s is that (looking at the
camera front) the plastic ledge under the right side of the prism mounting
platform (over the lens mounting button) is often broken out or cracked.
This is the piece in which you will find a little translucent housing for
the infamous f stop illuminator. I did not notice this when I bought mine.
I suspect this results from clipping the plastic corner with the lens
mount when rapidly changing lenses. I fixed mine with a little black
liquid rubber--just enough to keep dust out. In my case, there was no
effect on camera performance, but this problem may indicate hard use.
Since then, I've been conscious of this problem and when inspecting F3
bodies found the same problem over and over again. Here's a place where
Nikon should have used metal rather than plastic!
Tony Galt
On 17 Jan 1998, ERNEST TRENGGONO wrote:
2. What are the specific inspection need to be performed on a F3,
knowing that it could have been
used heavily?
From: Jean-David Beyer jdbeyer@exit109.com
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Calibrating Weston Master II
Date: Fri, 06 Feb 1998
Richard Knoppow wrote (in part):
tlt@lexis-nexis.com (Troy Tanner) wrote:
I have a Weston Master II meter that appears to work however, I don't
know if it is accurate. Anyone know where I can have it checked for
accuracy or recalibrated?
Best Regards,
Troy
----
Hi Troy, You might try Quality Light Metric 213 467 2275 They are
in Hollywood and have a good reputation.
However, you can check the meter by comparing it a known good meter.
Either a self-contained meter or a camera with TTL metering can be
used. All you need is an evenly illuminated surface which is large
enough to fill the field of view of the two meters.
Bear in mind that if you have more than one meter, you can drive yourself
crazy trying to compare them. This is because they may have very different
color sensitivities. Selenium, cadmium sulfide, and the various silicon
cell detectors all have different color sensitivities. My cameras (with
meters) are pretty well calibrated, as are my hand-held meters. But
comparing them can indicate up to about 2 stops difference in luminance
when measuring the same target if you are not careful. I have found that
the target should be a neutral color (a gray card, or a white card are
fine) and they should be illuminated by sunlight (to get the response the
meters are expecting). When I do that, the meters I have read within
about
1/3 of a stop. But using incandescent, fluorescent, sky-light (with no
sun), or measuring colored objects (pale blue wall in one of my rooms),
the vast differences obtain.
--
Jean-David Beyer
Shrewsbury, New Jersey
Date: Tue, 10 Feb 1998
From: "Arno G. Weiss" weiss@sendai.astr.tohoku.ac.jp
Subject: Re: how to inspect a used body?
Bischoff bischoff@bora.dacom.co.kr wrote:
I am planning to buy a used body. By the way thanks to all those who
advised me on the best choice. Can somebody tell me what are the basic
things to check before buying, to make sure it is in good condition? (I am
after a mechanical body).
Check foremost the following things:
1. accuracy of shutter times. If possible, get it timed using an
electronic timing device (some dealers have that). Otherwise, shoot a
roll of SLIDE FILM [not prints!], varying f-stop/time combination
(keeping exposure constant), to see if there are any rough
inconsistencies.
1a. accuracy of short times -- sometimes, on an old mechanical body,
short times are not executed properly, resulting in a partially
unexposed negative/slide. The film test above will check this.
2. accuracy of flash-sync. shoot a couple of frames (on film) using
flash, at fastest sync speed and longer times. see if the flash
really fires on time, and not too early or too late. (Of course,
using a faster time than x-sync with flash will naturally result in a
partially unexposed negative/slide...)
3. metering. Check that the metering is consitent with e.g. another
camera or hand held meter (e.g. using a grey card) OVER A RANGE OF
EXPOSURES (light levels) -- a consistent offset is ok (can be
compensated for by adjusting ISO on the body), but every inconsistency
over a range of luminosities will make you unhappy.
4. overall condition. Check for obvious damage external and internal
(e.g. shutter curtain/blades), signs of battery leakage in the battery
compartment, misalignments in the finder, etc. If you see any of
this, reject.
Best to get some return policy (no questions asked) for a couple of
weeks. Otherwise, include the risk of anything that you
couldn't check for turning up later in the price.
Best regards,
Dr. Arno G. Weiss
Astronomical Institute, Tohoku University, Aoba, 980-77 Sendai, Japan
From: Kerry Thalmann K.Thalmann@worldnet.att.net
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Where find front standard screws?
Date: Thu, 15 Jan 1998
Hi David,
Funny you should ask. I have relied on two companies for parts for my
do-it-myself camera projects, and I have received new catalogs from both
this week. The first is Small Parts, Inc. (800-220-4242 or
smlparts@smallparts.com). Among other things, they sell nickel plated
brass thumb screws in sizes from 4-40 - 1/4-20 and nickel plated brass
thumb nuts in the same sizes. The second company is Reid Tool Supply
Company (800-253-0421). Their main catalog is chock full of great parts
for do-it-yourselfers, but of even greater interest is the new Jan/Feb
1998 New Product Supplement that just arrived today. They have greatly
expanded their already extensive line of knobs, thumb nuts and thumb
screws. Many now come in stainless steel, brass and aluminum in a
variety of styles. They also now come in many of the smaller sizes
useful for camera projects. Thumb screws from 4-40 - 1/4-20, thumb nuts
from 2-56 - 3/8-16 (also metric sizes). You should find something that
not only fits, but even comes close to the finish and material of the
original (not a perfect match, but passable). Of course, I have no
affiliation with either company except as a very happy customer of both.
Kerry
http://www.ferrario.com/ruether/articles.html
http://www.fcinet.com/ruether/slemn.html [old site?]
http://f-server.cs.hks.se/~nicke/private/photo/lenstest/
http://www.par.univie.ac.at/~bob/photo/
http://www.cmpsolv.com/photozone/
http://www.ai.sri.com/~luong/photography/35mm/
http://i31www.ira.uka.de/~klaus_s/LensSurvey.htm
http://ptolemy.eecs.berkeley.edu/~murthy/Canon.html
http://home.hkstar.com/~peteln/bobby/photo.html
http://www.phys.rug.nl/mk/people/aue/nikon/grover.html
http://i31www.ira.uka.de/~klaus_s/lenssurvey.htm
A postscript version of the USAF 1951 testchart is also available
by anonymous ftp from butler.hpl.hp.com. See the directory
jacobson/photo.
rec.photo.marketplace
From: Walrik Walrik@freemail.nl
[1] Re: Nikkor Zoom-Best single, general purpose lens?
Date: Tue May 12 15:00:39 CDT 1998
Marc G. Koenig, M.D. wrote: > > I think I have decided to buy the Nikon N70. If I only buy one lens for > general purpose, what is recommended? I would like to keep it under $600 > and since it be my only lens for now, size and weight are important > considerations. I was thinking about the 28-200mm. Is the 28-120mm a > better choice? How do they compare on size/weight and quality? Are there > others you would recommend? Thank you very much. > Marc Koenig > marck@inetnebr.com Hi Maybe you get a little wiser from those links: http://cameraquest.com/links.htm http://home.ait.ac.nz/staff/rvink/photo.html http://www.webnw.com/~camera/nikon-lens.html http://www.zaiko.kyushu-u.ac.jp/~walter/nikon.html http://math.amu.edu.pl/~modrzew/menuen.html http://home.ait.ac.nz/staff/rvink/nikon.html http://f-server.cs.hks.se/~nicke/private/photo/lenstest/lenstest.html http://www.phys.rug.nl/mk/people/aue/nikon/grover.html
Bye bye
walrik
From: vrae@hotmail.com
Newsgroups: rec.photo.misc
Subject: How do you test lens sharpness?
Date: Tue, 26 May 1998
> I would like to test the sharpness of my lenses. I've got a 17-35, > 28-105, 70-200 and a 300mm. I read once that shooting the classified > section of the newspaper was a good way.
There are many, many ways to test optical lens quality (so many that even
those that do this kind of thing for a living can't always agree...). There
are what I'd call comparative tests ("gee, my 28-105 is sharper at 80mm than
my 70-200") and absolute tests ("at 50mm and f/4, my 28-105 zoom resolves 70
line pairs per millimeter at the center, and 52 lp/mm at the worst edge").
First, it helps to decide what you want to test. Resolving power is important
(and is perhaps easiest to test). So is contrast, light fall-off (uniform
edge to edge brightness), flare control and freedom from distortion. Each of
these parameters will vary, depending on aperture, near focus/far focus -
even things like temperature, type (and age) of film, etc...
Then, you'll need a set of test charts. I use the one from the Edmund
Scientific company (609-573-6250, Resolving Power Chart, about $20). The
Rochester Institute of Technology also makes a very good test chart that
you'll see mentioned frequently. You might want to have a few of these charts
depending on how seriously you plan on testing.
The next step is to setup your test environment. You'll need a temperature
stable area where you can mount your camera and the target at standardized
distances. Many people recommend a distance of 25x the lens focal length for
longer lenses, or 50x focal length for shorter lenses. To the extent that you
keep the image size constant, you'll find it easier to compare different
lenses' performance.
It's very important that the camera (actually, the film plane) and the test
chart be kept absolutely parallel to one another. If you get edge results
that differ significantly, suspect parallelism problems.
Make sure you use the same film for all tests. Most people use a slow, fined
grain slide film like Velvia. If you are comparing lots of lenses, try to
shoot film from the same batch, and try to have your processing done together
(all rolls in the same tank).
For lighting, I personally prefer electronic flash, since the short duration
of the flash helps minimize any camera motion (of course, you're using the
sturdiest tripod you can get your hands on for all this...). Plus, since I've
calibrated my flashes quite closely, I can verify that f/4 is letting in
twice the light of f/5.6, for instance.
Take multiple shots at every lens opening, being sure to focus very
carefully.
Use your camera's mirror lock-up and self timers (if so equipped) to
minimize camera motion. Take off any filters. Some people include a
color/gray scale so that you can verify exposure, too. If the images of
the test chart is too small, you can either move closer or use multiple
test patterns. Make sure you keep track of all exposure/distance
information so that you'll be able to correlate lens performance later on.
When you get the slides back, you'll need a microscope capable of
somewhere around 150x magnification. Look at the slides under the
microscope and you'll see that somewhere along the chart, the individual
lines stop looking like individual lines, and sort of blur together. With
this number in hand, you can easily compute lens resolution. You'll
probably want to make yourself a chart at different lens openings, and at
center versus corners. You may also want to try different distances
(especially for macro lenses).
That's just a small introduction. To learn more, you might want to get
copies of the procedures that the big photo magazines use, or pick up a
few books on optics. As you can see, serious lens testing is a
time-consuming, sometimes complex process.
Good Luck, and be sure to share the results of any tests you perform!
Date: Fri, 22 May 1998
From: "Roland Vink" roland.vink@ait.ac.nz
Subject: Re: More on dust (but this time in an FM2T)
> ... while travelling aroung Madagascar my FM2T picked up quite a bit > of dust in the mirror box (my F90x seemed to fair better on this score). > When I look through the finder there are all these really ugly black > flecks. I have carefully dusted within the mirror box with a blower > brush but with little success. Is it possible that dust can get within > the prism? And if so, can I somehow open it up myself?
Neil,
The dust you see is on the surface of your viewfinder screen (dust sitting
on the mirror would not be in focus and would not show up, except for a
slight loss of brightness or contrast in the viewfinder).
Use a clean brush to dust the lower surface of the viewfinder screen, at
the roof of the mirror box. If that does not work, the dust is on the
upper surface of the screen. To clean the upper surface you need to
release the frame holding the screen in place so you can remove the
screen. If you have ever changed a viewfinder screen, you will know what
to do. If you haven't, either contact me directly, or take the camera to
a nikon servicing agent, it should only be a 5 minute job.
Roland.
Date: Mon, 08 Jun 1998
From: raoul@olympus.net (Jeffrey E. Benedict)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Do lens sometimes underexpose?
keithw@southwind.net wrote:
> >I just got some pictures back from the lab that were perhaps 2 stops > >underexposed from what I thought they would be. I was using the 180 lens > >for the Mamiya TLR. I normally use the 135 lens for my portrait work but > >decided to use the 180 for a tighter head shot. I had the shutter > >overhauled about 2 yrs ago and haven't used it a whole lot lately. I was > >using shutter speeds 125 and 60 sec. Do the shutter speeds in this range > >get stuck on the higher speeds?
Time to do a test! Load up a roll of film, stick the camera on a tripod
and point it at something. Put the 135 (or another lens you are satisfied
with) and shoot half of the roll at 1/15, 1/30, 1/60, 1/125 and 1/250.
Put the 180 on and shoot the other half of the roll in the same manner.
(Obviously, adjuct the f/stop for the correct exposure) Develop the roll
and make a contact. Each of the photos should look exactly the same. If
the 180 looks slow, work the shutter a whole bunch of times and make
another test. If the 180 still looks funky, send it in...
Jeff
From: Lanier Benkard lanierb@econ.yale.edu
Subject: Response to What's the best way of testing a used lens?
Date: 1998-06-22
As far as inspecting the lens goes, someone mentioned holding the lens to the light, which is a start, but a *much* better test is to take a small flashlight and shine it through the lens. This will show ALL the lens's defects right away. In fact, after doing this the first time, you will probably find yourself going back to your other lenses and checking them out too because you will likely see a lot of crap that just doesn't show up any other way. If the lens has the slightest bit of cloudiness anywhere you will see it with the light. Of course real-world tests are also important. The light just helps with initial inspection.
From: Scott Eaton wseaton@mindsprin.com
Subject: Response to What's the best way of testing a used lens?
Date: 1998-06-19
One of the simpliest checks for any lens is to simply hold it up to the light and see how many defects are in the glass. You can also check for lens fungus that way.
One thing that most photogs NEVER check with older lenses is the functionality of the apeture diaphram. By default lenses are wide open but you rarely see then when the apeture is closed to a certain F-stop. 9x out of ten photographers blame their shutters for bad exposures when in fact it's the diaphram sticking open. While holding the lens in your hand close the apeture down all the way and then manually work the diaphram open and closed. The motion should be smooth and not stick.
As an example, about 50% of all 35mm off brand lenses (Tokina, Tamron, Vivitar) that I've used has severe diaphram problems. MF can be just as bad because the components are larger.
rec.photo.misc
From: "Only Me..." dgreg@globalnet.co.uk
Newsgroups: uk.rec.photo.misc,rec.photo.misc
[1] Re: Lens Advice for a beginner
Date: Fri Jun 26 08:44:33 CDT 1998
K.C. Mushambi wrote in message ...
>Should I try to find a zoom lens, or a few fixed focal length ones? I >found a ~80-200mm (Sigma) and a ~35-135mm the other day (I'm not sure what >f-stop though...is that the right term, f-stop?). Would those be good >buys? I don't have much money, and would probably be buying used. Should I >look out for anything when checking them out? What brands should I avoid? > >I am mainly interested in portraiture, still life, close ups, and >landscape in B&W.; > >thanks > >kuda
Your choice of lens depends upon what you wish to photograph, and how
important quality is to you. If you have a very form idea of what you want
to shoot, buying separate (prime) lenses will give you better quality
than a
zoom lens generally, but modern zooms are good, and shouldn't cause you a
problem, unless you are being very critical about quality.
Firstly, with the subject matter you have specified, you would not
ordinarily want a long telephoto lens, or zoom, and the 35~135 sounds like
it would do everything you want. Quite wide for landscape, and medium tele
for portrait. However, try to find a lens that offers a macro (close focus)
facility for your close up work. A better bet would be a zoom with a 28 mm
wide setting though, as 35 is really a bit too restricting for landscape.
Fortunately, lenses for your camera aren't too expensive, as a quick
look in this weeks AP has just informed me, e.g. second hand Vivitar 28~105
#80. That would be a good lens for you if quality isn't paramount. As for
quality, try to stick to a reputable manufacturer, i.e Sigma, Tamron etc.
and you shouldn't go far wrong. Also, try for the fastest lens you can
afford (lowest F-stop number - yes you were right about that :-))
Personally, I would stick with these two (Sigma and Tamron) as they appear
to be about the best third party lens manufacturers, and offer good value
for money.
What to watch for? OK, if your buying zooms, avoid any with extreme
slack, or play in the zoom mechanism, especially if it's a one touch design
(single, combined zoom and focus ring) as this indicated heavy use, and/or
possible damage. Focusing, and zooming (on a manual lens) should be firm,
but silky smooth; if it's not, reject the lens. Check that the aperture
diaphragm is working ok. remove both lens caps, and look through the lens.
Then rotate the aperture ring to ensure that the diaphragm moves as you
select each f-stop. Check (visually) that the lens elements aren't marked
in any way. There's no reason for the glass to be damaged in any way, even
if the lens has been used professionally, and if it is, again reject it.
Most people take care of their gear, and will fit a UV or Skylight filter to
their lenses, simply to protect the front element, so unless the lens is
REALLY cheap, don't buy one that's marked. Cosmetic damage may not be
indicative of a bed lens, and if the above checks are ok, it's purely a
matter of choice, especially if there's a warranty with the lens - try to
avoid a tatty looking lens though, as even if it works fine, it's a sign
that it's had a hard life. Also look out for mould and fungal growth inside
the lens, on the lens elements.
Check that it focuses OK: That infinity can be focused, and that
distances on the scale roughly correspond to the real distance, at all focal
lengths.
Finally, check that it meters ok. To do this, point your camera at a
wall in the shop your buying the lens from, and using your 50mm, take a
light reading at various apertures (your 50mm will be much faster than the
zoom, so start at the lowest that the zoom can be set to). Write down the
readings (shutter speeds your camera suggests), and then try the zoom set at
50mm, or the nearest you can get to 50mm. If the zoom doesn't have a 50mm
setting, move closer to, or further away from the wall to get the same
amount of wall in frame etc. Your camera should suggest the same shutter
speeds for each aperture with the zoom lens (remember to use the exact same
part of the wall,and that the lighting hasn't changed). If there's any
difference, and you're sure that you're sure 50mm is OK, then reject the
lens.
If the lens passes all of the above, you shouldn't have too much to
worry about.
David.
From: gmac@papercity.win-uk.net (Geoff Mackenzie)
Date: Mon Jun 29 11:12:59 CDT 1998
[1] Re: Russian cameras
DavidM (dmc@cyburban.com) writes: >oricum@hotmail.com wrote: >> >> mvictoriag@aol.com (MVictoriaG) wrote: >> > >> > I have a KIEV60, med format. >> > >> > >> >> any experiance usig it(TTL meter OK ? curtain shutters working ok?) becouse I >> want to buy one for landscape pictures.Lenses are sharp? >> Adrian Sorescu >> >Why do you assume that just because his lenses are sharp yours will be? >Quality control varies from lens to lens.
I'm not familiar with the Kiev60, so I may be talking
rubbish....but I assume it has interchangeable lenses? If so,
the recommended procedure a good few years ago (when quality control
in general, not just for Russian cameras, was nowhere near as good
as it is today) was to take a body from the dealer out into the
street, put it on a tripod, and run off a roll of film using a
different lens for each exposure (making a note of the serial
number of each lens, of course!). Then back to the darkroom, see
which exposure was sharpest, then go back to the dealer and buy the
corresponding lens.
Geoff
From Nikon Digest:
Date: Fri, 04 Sep 1998
From: Vera Britto fiatlux@umich.edu
Subject: what to check for when buying lenses
Someone had asked about what to check for
when buying lenses, check out tamron's web site.
there's a whole page listed of advice for how
to examine a lens, test it, and what to look for.
http://www.tamron.com/tamhome.html
Vera
Subject: Re: How to test a lens
From: "Jim Williams" jlw@nospam.net
Date: Sat, 24 Oct 1998
>What is the best way to test or compare a lens (or lenses if we are >comparing)? > >I figure the best thing to do is to take the same picture with both lenses >and then compare (duh!), >but, is there anything in particular than makes the comparison process >easier? >I mean, Is it better to shoot landscapes, portraits, architecture... to make >the comparison? > >What elements (in the picture) should be present (and where) to make a goo >assessment of a lens?
There is more B.S. on the 'net about "testing" lenses than probably any
other photographic topic (except maybe Nikon vs. Canon, or the mythical
supremacy of Leica.) Here's my take:
-- Start by thinking about the kinds of pictures you like to make. Decide
in which ones lens quality would be most critical. For example, if you like
to do family photos, sports, and portraits, I'd guess the portraits are the
most lens-quality-intensive; people will forgive a bit of blur in your
great shot of your kid sliding into home plate, but in a portrait you're
really going to want to see those eyelashes sharp.
-- Think about all the ways you USE your pictures, and decide which uses
put the greatest emphasis on lens quality. Again, if you mostly shoot print
film and get 4x6s minilab prints, but occasionally "get serious" and burn
through a roll of Kodachrome 25 with the hope of getting a shot worthy of
an 11x14 Ilfochrome print, the slide film is the most critical. (In fact,
slide film is better in general than color print film for lens evaluations,
because its emulsion layers are thinner and capable of rendering more
detail. Black-and-white film is also a good choice, but doesn't give you
a chance to look for defects such as color fringing.)
-- Now, set up a repeatable test situation (or, more likely, several
situations)incorporating your "most demanding" subject types. Take all the
precautions you'd normally take when you're aiming to produce your very
best results: sturdy tripod, good lighting, careful focusing, etc. Load up
with the film you'd normally employ for your most critical use, as
identified above (probably a slow-speed, fine-grain slide film.) Take a lot
of shots with both lenses you're considering, making sure you cover both
wide and stopped-down apertures; close and far distances, and any important
special capabilities such as macro focusing.
-- Once you've gotten your film processed, examine it under conditions that
*exceed* the most critical use you identified. For slides, that probably
means examining them directly with a *high-quality* magnifier in the
10x-15x range... or more, if you've got it. Look for: crispness of
high-contrast edges, such as eyelashes; good textural definition in
low-contrast areas, such as skin and fabric; and absence of defects such as
color fringing and flare (check some "specular highlights" such as the
glint in eyes or jewelry.) If you're interested in photographing buildings
and other architecture, your test pictures should include a suitable
subject so you can check for linear distortion (straight lines should be
straight.) If you often shoot against the light or into light sources
(stage shows, for example) make sure your test shots include a similar
situation, so you can check for ghost images and streaks. Also, pay
attention not only to the sharp areas, but to the appearance of
*out-of-focus* areas. The way they look -- something the Japanese call
"bokeh," which has been discussed to death here on rec.photo -- can make a
big difference between pleasing and mediocre results, especially in such
"atmospheric" pictures as informal portraits and scenics.
This kind of evaluation won't tell you which lens will score the best
numbers in a magazine test. But it will tell you which one will be more
likely to "score" well in characteristics YOU care about, when used for the
kinds of pictures YOU like to make.
rec.photo.equipment.large-format
From: bg174@FreeNet.Carleton.CA (Michael Gudzinowicz)
[1] Re: Schneider 90mm f8
Date: Fri Nov 27 12:55:17 CST 1998
Tracy Hamby h820@pe.net writes:
>I have a Schneider Super Angulon 90mm f8 that I recently purchased a new >shutter for from Schneider. All of a sudden it's not as sharp as >before. I was told that the lens should be "centered". Is this >something I can do myself?
Maybe. The term refers to the alignment of glass elements in each cell,
and cell alignment. The centering is done at the factory when they finish
the edges of the elements, glue elements together, machine the cell mounts
and mount the glass. It is possible to create a centering problem by
dropping the lens and damaging the shutter, in which case the optical axis
of each cell is no longer in alignment with the other. If the lens isn't
sharp in the new shutter, the shutter may have been damaged. Alternatively
the spacing might be off, or there might be a fingerprint or residual oil
on the inner/outer cell surfaces.
For a quick check on shutter condition, place a sheet of glass on a stable
table and shim it with sheets of paper so it is level in every direction.
Place the lens on the glass sheet, and place another glass sheet over the
other cell, and check if it is parallel. If the shutter has been damaged,
it won't be, and Schneider will replace it. If it passes that test, then
check the front to rear cell spacing in the old and new shutter. You can
just measure the distances from the outer edges of the cells with a
machinist's caliper.
If you want to look for a centering problem directly, there are a couple
of approaches which require an improvised optical bench. If the lens is
focused on a small bulb filament covered with foil with a pinhole in it
(star image), and the lens is rotated, if the image moves around in a
small circle when viewed with a microscope, it is decentered. The degree
may/may not affect performance. If the image shows coma on axis, you have
a real centering problem. The direction and size will remain the same
across the field unlike common coma which runs out radially from the lens
axis. If the star image is placed off-axis and the lens is rotated, its
orientation will vary and size will increase/decrease with rotation.
Note that the image wander may not be present if more than one surface is
decentered permitting cancellation. However, decentration coma may still
be marked.
Another problem which will arise if the cells/groups/elements are off
axis, is that the plane of focus will no longer be perpendicular to the
lens axis - it will be tilted with the camera in "neutral".
If you can't sort out the problem (hopefully, its a fingerprint), Steve
Grimes might be able to resolve the problem and repair it.
rec.photo.equipment.misc
From: rmonagha@news.smu.edu (Robert Monaghan)
[2] online Re: Macbeth color checker
Date: Sun Feb 07 04:10:51 CST 1999
see macbeth color checker URL in links page at:
http://www.smu.edu/~rmonagha/mf/links.html
both monitor calibration and printer versions are out there (assumes you
havea access to a color printer)
for most general testing of films, the actual colors don't matter much as
long as they are stable and over a broad enough range. I've used color
sample brochure materials from paint stores as a no-cost substitute. A
grey card (Kodak) some test charts downloads to laser printer (see links)
and some color swatches, and a piece of posterboard and matte spray, and
you are all set ;-) The extra color sample brochures make it easy to
compare against slides or prints without pulling out the test chart
if you don't like that freebie approach, the links site to candela corp
also has various RGB test color combinations you can print out instead,
but the plastic paint samples are more stable colorwise esp in sunlight
than most color ink or color laserprinter printouts IMHO ...
see http://www.smu.edu/~rmonagha/broncameratest.html for more on lens tests
HTH - regards bobm
From The Nikon Mailing List:
Date: Fri, 07 May 1999
From: Todd & Sharon Peach tpeach@gte.net
Subject: testing a used camera body
Xiang had questions about testing a used FE.
When I sold cameras retail (put myself through college), we had a five
minute routine we'd do at the counter for SLR camera trade-ins:
* Look at camera externally for cosmetics, missing parts, bent pieces.
* Look at film chamber and mirror chamber for cosmetics, scratches,
burrs, etc.
* Fire the camera at every shutter speed; listen to sound to see if
each
speed is half / twice the previous one.
* Mount a flash, open the camera back, point at white wall, fire at
x-sync. Verify that the curtains are clear of the opening when flash
fires. Bump the shutter speed up a notch, fire again. Verify that one
shutter curtain casts a shadow when flash fires. (this pair of tests
gives you a very crude calibration that the shutter speeds are accurate
at that point in the scale.)
* With a known good lens, fire the camera with the back open at various
apertures. Check to see that the aperture stops down crisply (rare but
troublesome flaw)
* If the camera has / can take a motor drive, check it's function.
* Do a "sunny 16" check (this was Phoenix, it was always sunny). Sunny
16 rule says that the exposure for an average gray subject in sunny
daylight is f/16 with shutter speed = to ISO. Check the reciprocity at
this time: change aperture one stop and shutter speed indicated should
change one stop as well; walk through a half dozen stops this way if you
can. Change ISO setting several times and repeat. Change exposure
compensation and verify effect.
* With a known good lens, verify focus in the viewfinder matches
distance indicated on the lens barrel. Verify parallelism of the
viewfinder path by focusing on a flat object like a wall. Check that
the Left and Right, Top and Bottom of the focus screen are in focus at
same time (this is subject to how "parallel" one can hold the camera to
the wall). This will only catch gross errors.
* Actuate every other control on the camera at least once: self-timer,
DOF preview, AE Lock, multi-exposure, etc.
All of the above can be accomplished in real time without film, using no
test equipment. It assumes you have some knowledge of the camera in
question and access to some known good lenses, etc. The "focus" shifts
a bit if you're examining a lens, but the idea is the same.
Since you have 14 days, I guess I'd add:
* Repeat parallelism test more carefully with film. Shoot wide open
with a known good lens.
* Verify exposure accuracy with slide film. Use a film that you are
familiar with.
* For TTL flash systems (not on the FE), verify it's accuracy with
slide film as well.
* Shoot some clear blue sky with slide film at various shutter /
aperture combos. This should show any shutter bounce problems.
As I write this note, it occurs to me that there's probably some web
pages out there with some of the same common "wisdom" (I hope it's
wisdom). Robert Monaghan's page at:
http://www.smu.edu/~rmonagha/mf/index.html
probably has something, but I didn't read through all 100+ links just
now.
-Todd--
Todd & Sharon Peach
Seattle, Washington (zone 7)
tpeach@gte.net
http://home1.gte.net/tpeach/NoPlaceLikeHome.htm
From Rollei Mailing List:
Date: Sun, 13 Feb 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Leica acquisition question
At 09:24 AM 02/13/2000 -0000, you wrote:
>Be advised that you should view any older Leica lens through a bright light >source at wide open aperture to determine the degree of fogging. It is >likely to have some. I understand that this resulted from the type of >lubricant employed by Leitz. >----- Original Message ----- >From: jerryleh@pacbell.net >Sent: Sunday, February 13, 2000 4:08 AM >Subject: Re: [Rollei] Leica acquisition question >
This is a pretty common effect with all lenses. I am not sure of the
source of the haze, it may be from the anti-reflection paint inside lens
cells, or from lubricant. In any case, it comes off with ordinary lens
cleaner. This haze seems to be nearly universal in sealed cells of lenses
of some age. I think one reason some older lenses have a reputation for
low
contrast is more due to this haze than to lack of coatings or design. The
internal haze can absolutely destroy contrast.
AFAIK, Leica lenses are not too difficult to get apart to clean. Pay
attention to how the lens comes apart and put everything back as it came
out. Don't worry about de-centering. Centering of elements in a mount are
determined by the construction of the mount and the glass will be
automatically centered if the reassembly is done carefully making sure the
glass is seated before tightening.
Inspecting lenses with a flashlight as described here is a very good
practice. It will show up not only haze but evidence of flaking paint and
blemishes on the glass.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: "Q.G. de Bakker" qnu@worldonline.nl
Newsgroups: rec.photo.equipment.medium-format
Date: Fri, 2 Jun 2000
Subject: Re: Hasselblad "dream" rig...
.....
Buying lenses used can be a fine way to save money. There are some very
good
ones about. You will definitely have to shop around.
The usual caveats apply. Check the glass for marks. Hold the lens to the
light and check for debris, or even fungus, inside the lens. (But don't
worry about a little dust). Check the mount for excessive play. A little
play will always be present. Extend the lens to its fullest to do this,
and hold the lens by the front part (front bayonet region) in one hand,
and the back (camera bayonet region) in the other, and twist (very)
gently. Dont hold the lens by any of the moving parts (shutterspeed-,
aperture- or focussing ring). Check the focussing action for eveness.
Check the setting rings for play and smooth action. Engage the depth of
field preview lever, and run through all apertures, whilst looking through
the lens to see if the aperture will form a regular pattern when closing.
And check the leafshutter. Put it on a body, and cycle through all
shutterspeeds. Listen and look carefully. The final, and best, test would
be to expose some film, running through all shutterspeed - aperture
combinations. Have the film developed and check if of all negatives/slides
show equal density.
....
Have fun!
From Contax Mailing List:
Date: Tue, 30 May 2000
From: "Bob Shell" bob@bobshell.com
Subject: Re: [CONTAX] Rx going to Hospital
It happens. You'd be amazed at how many brand new cameras come in to us
for testing and turn out to have something serious wrong with them. As
cameras get more and more complex it becomes more and more difficult to
assure quality control. Cameras received with problems have come from the
most expensive brands and from all the others. One very high priced SLR
was never written up in Shutterbug because the manufacturer never could
get us a sample on which everything worked!!!
Bob
From: "Neil Harrington" no.spam.wanted@thanks.net
Newsgroups: rec.photo.equipment.35mm
Date: Sat, 17 Jun 2000
Subject: Re: How do you test camera lens for quality
"Brian" bclark@es.co.nz wrote
> Lets face it Tony, all lens give reasonable result (they wouldn't > sell if they didn't). What I'd like to know is how to tell the > difference in a high quality lens and one that gives average results. > What are the best subjects to photograph and how do I tell by looking > at photos ?
Probably the best all-around test is to photograph a brick wall (apartment
house, etc.) in direct sunlight. Slides are best for this, as they are
easier to examine with a strong magnifier than any sort of negative, and
will show any light fall-off best. Don't bother trying to examine prints
as the results will be more or less meaningless.
Shoot from a tripod and make sure the wall is perpendicular to the lens
axis. Shoot one frame wide open and one at each full f-stop, down to f/11
or so. Not much point in going to much smaller apertures as you probably
won't see much if any difference beyond f/11.
If using a zoom lens, repeat at each marked focal length, or as many as
you're interested in comparing. It's best to move the camera back as you
go to longer focal lengths so as to keep the bricks about the same size;
otherwise it can be hard to compare them in the final results.
Try to get all the shooting done as quickly as possible, so that the sun
doesn't move too much between the beginning and end. If repeating the
tests another day, try to do at at about the same time so that the sun
will be in about the same position, preferably behind you and to one side,
say about the 4 or 5 o'clock position, or 7 or 8 o'clock. Don't do it if
the light is hazy as that will reduce contrast and make comparison
difficult or impossible.
Examining the slides will show you how sharp and contrasty the lens is
from corner to corner, how much this changes from one f-stop to another,
how much distortion the lens has at various focal lengths, how much light
fall-off there is wide open and at what aperture this clears up, etc.
Obviously this is all relative, so it is useful if you have a lens known
to be of excellent quality that you can use for comparison. If you have a
50mm standard or macro lens, that should serve well, as most of these are
optically excellent.
You may also be able to find USAF lens resolution charts somewhere.
Photographing these at some multiple of your lens's focal length (usually
50x the focal length) and examining the negatives (preferably B&W;) with a
powerful magnifier (preferably 20X or so) will allow you to read lens
resolution in line pairs per millimeter. This is the same method that Pop
Photo uses to test lenses which for one reason or another they cannot test
with their standard MTF procedures.
A problem with this is that the test is rather subjective, since
determining which block of line pairs on the chart is the last to show
them distinctly is not as easy as you might think. Also, it will tell you
nothing about distortion or light fall-off. Really I think the brick-wall
test is best.
Neil
[Ed. note: besides being a noted pro/glamour photographer, photo workshop
instructor, and editor of shutterbug and author of various books,
Mr. Shell is also a noted former repairperson...]
From Contax Mailing List:
Date: Fri, 21 Jul 2000
From: Bob Shell bob@bobshell.com
Subject: Re: R: [CONTAX] OT help needed for a gift
> From: "Andrea Bracco" andibracco@tin.it > Reply-To: contax@photo.cis.to > Date: Sat, 22 Jul 2000 > Subject: R: [CONTAX] OT help needed for a gift > > I think you say "avoid the "lemon""... > thanks > andi
Andi,
Open up the camera back and look at the pressure plate. You can tell how
much film has been through a camera by how much wear shows on the plate.
(Except on Contax with ceramic plate). Look at the shutter, both before
and after cocking. On cloth shutters it should be smooth and tight,
no wrinkles. Look at neck strap lugs for wear, an indication a camera has
been carried a lot.
Take the lens off and set it to the smallest aperture (f/16 or f/22
usually) and on the Pentax push in the pin on the back with your finger
and make sure the diaphragm closes quickly and to the same size opening
every time. On the Minolta it is a lever which moves sideways and opens,
rather than closes, the diaphragm.
Compare the light meter in the camera to one of known accuracy if you can.
On both the Pentax and Minolta you set the ISO by lifting up on the
shutter speed dial and turning until the correct speed shows in little
windows on the top of the dial.
BTW, in spite of its name the Spotmatic does not have a spot meter. It is
full area averaging, as is the Minolta. The Minolta, as I recall, is more
center weighted than the Pentax.
Bob
[Ed.note: Mr. Erwin Putts is a noted Leica lens tester/reviewer...]
From Leica Mailing List:
Date: Mon, 14 Aug 2000
From: "Erwin Puts" imxputs@knoware.nl
Subject: [Leica] Re: Ultron decentring, was Re: 35mm Summicron, version
differences
Some Luggers expressed interest in detecting decentered elements with a
practical test. In fact only an optical bench or an interferogram can
detect decentering, but there is one field test, that will show
decentering, if done well. You need to take a night shot of a scene with a
row of lights spanning the whole image from a reasonable distance,
preferably 10 or more meters. The filmplane and the row of lights (a
parking area or an industrial complex that has lights all over a building)
must be aligned of course and that is the hard part, at least with an M.
But you can use the frame lines to make sure the camera and line of lights
are fully parallel to each other. If the lens has decentring, the left or
right part of the picture should show the lights with a higher flare and a
larger halo and a lower contrast. You need to expose correctly and enlarge
a bit, but this test will show decentering if it is severe enough.
Erwin
Date: Mon, 04 Dec 2000
From: Anders Svensson anders.-.eivor.svensson@swipnet.se
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens testing help
Blip skrev:
> Okay I buy a lens (Sigma 105 f/2.8 EX Macro) - after having looked at > the MTF sites and the personal-opinion sites and seen that the lens is > excellently rated. How do I test it to check that it's not a dog? Are > there any sites which will give me step by step info? Anyone here > help? > > TIA
Well, a very superficial way of testing the lens could be
to:
1. get slide film of a reasonably well known make that
performs consistently well. I like Agfa and Kodak, some like
Fuji very much. The film you are used to is the best, of
course. Print *film* can be used, but most people can not
judge color negatives very well. Paper prints are almost
meaningless to judge.
2. Get a tripod (borrow a really good one, if you don't have
a decent one already). Testing a 200 mm telephoto is
meaningless unless you have a good, stable support.
Then, get some kind of large marker pen and some white
material to write on - a small white board and a white board
pen (brush off) is ideal. This is so you can add a label for
every single shot, like "f5.6 - 200 mm". Without this
documentation, careful notes still must be taken and there
is still a risk of mixing up the images.
3. Find a brick wall and mark a aiming point (a "X" from
masking tape is great) at the same height as the camera
lens, when on the tripod.
Then, walk away from the wall a suitable amount, I suggest
as many feet as there are millimeters in the focal length
for ordinary lenses. Now, yours is a macro lens and close
range performance is probably what you are after - so you
should really test your lens at close range and with a
smaller test target. A "millimeter square" paper on a flat
surface could be used as a "miniature brick wall" for macro
lenses.
Make as sure as possible that the wall/target now is *at
right angles* to the camera. Aim the camera so the "X" is
perfectly in the middle. Put the white board with the test
info below the X so it can be easily read.
This is a easy way of aligning the camera so it is square to
the test target, and it is important that it is so - any
alignment error, and edge sharpness can't be evaluated at
all. If you want it to be "perfect" use a measuring tape and
triangulation, however, eyeballing works well enough for me.
4. Take a reference image (or two) with a known, "good"
lens, one you already know the capacity of. This is to make
sure that there is nothing really wrong with the camera or
the film developing. Mark these with date, f-stop, shutter
speed and lens designation as well. Be methodic.
5. Start to shoot, methodically, boring images of the brick
wall with the lens you want to test. Make sure you do your
absolute best with manual sharpness setting, but you have to
let the AF set focus as well - see below. Shoot at least
nine images for a zoom. One each for shortest focal length,
longest focal length and one in between. Then, use at least
three f-stops, like fully open, f/8 and f/11. If you want to
check AF (more of a camera check than a lens check, IMHO),
do that on the largest possible aperture setting, you will
want to minimize positive DOF effects for that test.
The more combinations you get, the better, but *make sure
you annotate every shot* clearly on the white board or your
notes. It might be a good idea to shoot a few images with
the "reference lens" inside the test series as well but do
mark *every shot* perfectly legible. There is no way you can
be sure of what lens, f-stop and focal length setting (for
zooms) otherwise.
You may also move the camera and shoot a image diagonally
(at a acute angle, say 30 degrees or so) towards the tape
"X". Use AF for that shot. This shot will verify that the
lens and camera focuses spot on. If the X is sharp(est), all
is well.
6. When finished, develop the film and wait for it to
return.
Now, look at the images thoroughly. If you have followed my
advice with using a board with image data in every shot, it
would be easy to judge how sharp the image is for every
focal length and f-stop. It will be a bad lens indeed if the
text isn't legible :-). Otherwise, you will need to refer to
the notes you took.
Use a good loupe, and if you don't own one, a 50 mm normal
lens can be used. If you look at the image in a projector,
be aware that you add any fault of the projector or screen
setup.
Judging the lens's quality in absolute terms isn't possible,
of course, but as you have a few (two, at least)
known-to-be-good images on the film, I feel that you can use
the images for a relative comparison. Note that if the
"known-lens" images are sharp and well exposed, it is not
likely that there is any other explanation than a bad lens
if the real test images are bad. Optical performance isn't
the only lens problem, BTW, aperture precision is also a
possible fault. Any noticeable exposure density difference
is likely to be a lens variation, if the "standard lens"
works well.
Look for sharpness in the middle (expect that to be pretty
good on every image) and then look at the extreme corners
and compare sharpness there, both between themselves and the
middle. It will be a little worse, usually and that is
normal. If any corner is worse than another, it's more
serious (You *did* square up the camera, didn't you?).
Then, take a look at the brick mortar lines, and see so they
are parallel to the negative edges and isn't rounded. If
they "bend" either way you have distortion. Distortion is
not uncommon, but it has to be only a little of it if you
intend to use the lens for shooting, say, brick walls
(architecture) :-) Straight and level houses are really
good 3D test targets, BTW.
Use the diagonal shot to test the AF. If the "X" is
perfectly sharp and in focus, all is probably well. If it
isn't, but some other part of the image is sharp, something
may be less than satisfactorily with the AF mechanism.
***
This is not a "lens test", the way the testers do it, but I
would suggest that it is a passable way of making a
acceptance test of a new or used lens.
It is probably good enough method to help you win a warranty
discussion a little easier than if you just show some less
than perfect images and complain about the lens.
--
*************************
Anders Svensson
mail: anders.-.eivor.svensson@swipnet.se
*************************
Date: Wed, 10 Jan 2001
From: jgestar@my-deja.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How to test second hand lens
> Hi friends! > > How do you test a lens when you buy an used one? What things do you look > for?
First, twist the focusing ring of the lens. It should be smooth
through the whole range of focus. Roughness throughout indicates the
lubricant is drying up. An area of focus that is much tighter than the
rest indicates the lens may have been dropped rather hard (don't buy
it!).
Check the aperture blades for oil or grease (bad sign). Set the
aperture ring to f16 and push the auto aperture lever until the blades
close. Flick the auto aperture lever a few times. The blades should
move freely and easily. If the lever or blades have a lot of
resistance the lens may give poor exposures (don't buy it). Check the
aperture setting ring for roughness or stickiness. Like the focus
ring, it should be smooth through the whole range of motion.
Shine a small flashlight back through the lens toward your eyes (but
not into your eyes). Any problems with the glass will show up -
scratches, fungus, fungus that has been removed (looks like a chunk of
spider web got in the lens), dust, lens coating flaws, etc. Shine the
light through both ends of the lens. Make sure the outer lens surfaces
are clean before you do this. This test shows up flaws that may not
effect your pictures. Look at a few really good lenses to compare.
Look for any indications that the lens has been disassembled by an
amateur. Scratched bezels , burred screw heads, and scratches on the
aperture blades are all bad signs (don't buy it). Look for wear on the
moving parts of the lens, the auto aperture lever, the edges of the
aperture blades, and the lens mount. Excessive wear indicates a lens
that has seen a lot of use.
Finally, if you can get any return period from the buyer so you can
test it with film do so. When checking the film for sharpness don't
look at prints. Look at the negatives. If possible, shoot slide film
and look for sharpness and contrast of the lens. Compare to a lens
that you like on the same roll of film.
Finally, be patient. Another lens of better quality will eventually
show up.
Tom Gould
(jgestar@aol.com)
From Rollei Mailing List;
Date: Thu, 04 Jan 2001
From: imagineero imagineero@xv1100.com
Subject: [Rollei] testing focus by projection?
I've been trying to think of a way to test the lenses on my Rollei to be
sure they are both focused at the same point. Previously I had done this
by setting up the camera on a tripod with a target that is usually a piece
of newspaper. The paper is taped to a wall and the camera set at an angle
so that the distance from camera to the beginning of the paper and the
distance from camera to end of paper is different. I'm sure this doesn't
make much sense when I type it, but it is really very simple. I rack the
camera out to it's closest focus then move the camera around until the
center of the newspaper is in focus. I snap off a few shots with aperture
wide open, then develop the (slide) film. The camera is left exactly
where it was on the pod while I pop down to my lab that does 1 hour
slides. I come back and then adjust the viewing lens so that whatever the
focus point was in the slide is now the focus point in the view screen.
While this method works well it is time consuming. I recently thought
that I might use the camera as a projector to project a slide onto a wall,
and then adjust the viewing lens to be focused at that point. would this
work, or do lenses focus at a different point when projected rather than
when taking photo's?
Shaun
South Korea
From Rollei Mailing LIst:
Date: Thu, 04 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] testing focus by projection?
....(above posting quotes)
The easiest way to set coincidence is to cut a piece of ground glass to
fit the film gate. YOu can see the image directly that way and compare it
to the finder.
The depth of field method you describe is perfectly valid and may
indicate if the actual film plane is not at the gate due to bowing of the
film.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
POSTSCRIPT:
Snipping...
I forgot to mention this. I use the matt tape on clear glass. Run the
tape to the edge of the glass so the whole thing is located by the film
rails. You will need a fairly high-contrast image to see the optimum focus
point easily.
You can also use clear glass. Make a mark at the center of the glass
with either a thin marking pen or by scratching a cross on it. You then
check focus by using a loupe focused on the scratch or mark and adjusting
focus until the aerial image is in focus. Then move a little from side to
side. When the image is exactly focused on the cross mark it will not move
when when the angle is changed a little. This is an extremely accurate
focusing method but must be done carefully. If your eyes still accomodate
(mine don't) you must be careful to keep focused on the cross mark,
otherwise your eyes will tend to pull the aerial image into focus
regardless of where it is.
BTW, coincidence can be checked at any distance but you will need a very
distant object (half a mile minimum) to check for the infinity position.
From Rollei Mailing List;
Date: Thu, 04 Jan 2001
From: Gene Johnson genej2@home.com
Subject: Re: [Rollei] testing focus by projection?
Hi Shaun,
I'll add a method I got from someone either on this list or on ZICG.
Carefully put a couple pieces of matte scotch tape across the opening
where the film would normally run. get it nice and flat, and be sure
you have it across the same "rails" the film runs on. Use the tape like
a ground glass. Works great, and costs nothing. I like to do this on a
clear night on a tripod, with city lights way in the distance. I also
use a magnifier to make sure the image on the tape is as clear as
possible. It's kind of fun. Good luck.
From Rollei Mailing List;
Date: Fri, 5 Jan 2001
From: Richard Urmonas rurmonas@senet.com.au
Subject: Re: [Rollei] testing focus by projection?
> This has got me thinking..... to the best of my knowledge there is no > different adjustment for coincidence between close focus and infinity (nor > theoretically need there be). As long as the lenses are aligned at one > point they should be aligned at all others, right? I've always adjusted > mine at the closest focus point since there was least depth of field > there. Am I doing something wrong (probably not since my photo's always > have good focus after this adjustment). I am curious anyway.
Normal practice is to adjust the coincidence at infinity focus. This
gives the best resolution for lens-film spacing. Look at the geometry and
you will see. In practice infinity focus can be a problem as when you are
checking the setting you cannot go past infinity to check it is really at
the optimum focus. I generally adjust at 10 metres, this gives me the
ability to check optimum focus and also check the focus knob calibration.
Best object to use for infinity check is Venus. It is near enough to
infinity, reasonably bright, and a small circle. This gives a nice clear
focus indication.
When doing the adjustments I use a 30x "pocket microscope" which gives
enough magnification for good repeatability.
Richard.
Richard Urmonas
rurmonas@ieee.org
From Rollei Mailing List;
Date: Fri, 05 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] testing focus by projection?
you wrote:
>This has got me thinking..... to the best of my knowledge there is no >different adjustment for coincidence between close focus and infinity (nor >theoretically need there be). As long as the lenses are aligned at one >point they should be aligned at all others, right? I've always adjusted >mine at the closest focus point since there was least depth of field >there. Am I doing something wrong (probably not since my photo's always >have good focus after this adjustment). I am curious anyway. > >Shaun >South Korea
Nothing wrong at all. If the lenses are properly matched they should b
together at any distance and can be checked at any distance. Perhaps I
wasn't completely clear that a distant object is needed only for checking
the infinity stop position for both lenses.
I think for coincidence a distant object may be more sensitive since the
amount the lens moves to change focus increases with distance. So, a small
offset between the lenses will be more obvious for a distant object than
for a close one.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
[Ed. note: thanks to Christer for sharing this tip!]
From Leica Mailing List:
Date: Sat, 10 Feb 2001
From: Christer Almqvist christer@almqvist.net
Subject: Re: [Leica] focus inaccuracies: my test results
snip
>: the point of focus is >about 1-2 inches (2-3 inches on the slides, but the ruler is at roughly a 45 >degree angle) closer than the target (the area in which the RF perceived
snip
I have always found the method you use to determine if the camera
focuses correctly (i.e. taking pictures of a ruler at 45 degrees
angle) gives results that are difficult to interpret.
In my opinion it is better to draw a thick vertical line on a sheet
of paper and stick the paper to the wall. With the camera on a
tripod, at the distance you want to test, focus using the rangefinder
and make one picture. Then make four more photos, each time turning
the lens one sixteenth of an inch in the same direction. Then focus
again and take one picture. Then make four more photos, each time
turning the lens one sixteenth of an inch in the same direction, but
the opposite direction from the first row of pictures. Repeat the
whole thing for infinity (no need to turn lens in both directions
here!) and any other distance you want to check focusing for. Open up
the lens as much as possible to get shallow dept of field. It helps
to put small "post it" stickers on the lens with markings for 1/16th
inch, and you may want to include something in the picture telling
you which way you turned the lens, at least when you are
photographing lines on paper. Then develop the film and look at the
negatives with a good loupe. All my Leica lenses (21mm, 35mm and
90mm) focus percectly on both my M6s according to my test as per
above.
Chris
- --
Christer Almqvist
From: spammenotydavis@hkg.odn.ne.jp (Jim Davis)
Newsgroups: rec.photo.equipment.35mm
Date: Sun, 25 Feb 2001
Subject: Re: How do you test a lens for misalignment?
"J. Russell" xibor@mail.com wrote:
>Ok, let's make this question simpler, since my last post didn't get answered (grin). >A lens was dropped on a rock. The lens fell on the UV filter, but there is no >external damage to the lens. What is the accurate method of determining if the >optics are misaligned? > >THANK you.
Shoot a grid using a tripod. If you get the grid squared in the
viewfinder, it should be square on the neg. Do the test wide open, and
check that it's sharp all over, corner to corner. If you can't find
something grid like, just use a large rectangular piece of paper flat
on a board or something like this. The main thing is you want to
square it up in the finder and check sharpness all over.
webpage: http://www.kjsl.com/~jbdavis/
From: Kirk kirkdarling@mindspring.com
Newsgroups: rec.photo.equipment.35mm
Date: Sat, 24 Feb 2001
Subject: Re: How do you test a lens for misalignment?
xibor@mail.com says...
> Excellent, thank you. So, if a lens was tilted on some axis (misaligned), would that > show up as a blur on the grid at the edges of the frame? Would they be symmetrical, or > uniform? I hope to not confuse aberrations that were caused by the drop, and those > inherant in the design of the lens (it's a zoom lens, by the way).
Aberrations in the lens will most likely be, so to speak,
uniform...that is, the corners are likely to be uniformly unsharp for
a given aperture. However, a misaligned element (either from the
factory or from your drop) can appear to show the same problem if you
can't measure whether the unsharpness in one corner is in the same
direction as unsharpness in the opposite corner--or in the opposite
direction.
--
Kirk
From: Kirk kirkdarling@mindspring.com
Newsgroups: rec.photo.equipment.35mm
Date: Sat, 24 Feb 2001
Subject: Re: How do you test a lens for misalignment?
....
You'd need equipment to check the element alignment, which not very
many independent camera repairers even have.
You'd also have to dismantle the lens to locate any possible damage to
threads, bearing races (if your lens has any), etc.
Or you can just do some careful transparency taking on a tripod of
objects with detail from center to corners, like a brick wall, at
various apertures and compare them under magnification.
--
Kirk
From Rollei Mailing List:
Date: Fri, 30 Mar 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Another Optics question
you wrote:
>Darn, my camera did not have a problem with coma. I checked the test roll of >film I took yesterday, and saw that all negs were unsharp at one end... So I >guess the problem is the flatness of the film. Must check the camera. > >/Patric
Blurred at one end suggests the lens and film are not parallel rather
than film flatness. Check to see that the front standard isn't cocked a
little.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From Kiev88 Mailing List;
Date: Thu, 24 May 2001
From: captaincog@netzero.com
Subject: How to tell uneven shutter
The most noticeable way is to shoot a bright outdoors skyline shot,
or one that has scenery in it, but lots of sky. Then either,
underexpose by one stop, or use a filter at high speed. You will then
see vertical bands of color/exposure variations. The middle of the
picture will be darker than the edges, with the left side usually
being the lightest. I have been told that this is from the second
curtain being slow to respond behind the first curtain.
Hope I have answered your question,
Jeff Meyer
rec.photo.equipment.35mm
From: Bill Tuthill ca_creekin@yahoo.com
Date: Tue May 29 12:09:55 CDT 2001
Subject: Testing barrel/pincushion, distance?
In a relatively recent photo.net pissing contest, I spent time testing
the Yashica T4 Super for pincushion distortion. It had virtually none
near infinity, but pincushion was quite bad at close distances.
What optical properties would cause a lens to have different distortion
levels at different subject distances? Is it generally necessary to
test only twice, near infinity and near closest focus, or is it necessary
to test more than twice?
Also, how can I measure flatness of field?
From: ca_creekin@yahoo.com (Bill Tuthill)
Newsgroups: rec.photo.equipment.35mm
Date: 31 May 2001
Subject: Re: Testing barrel/pincushion, distance?
rmonagha@smu.edu (Robert Monaghan) wrote
> yep, sad but true ;-) - as y'all have discovered, it also varies by > focusing and zoom settings etc. as well as inherent in lens design etc.
For a great example of sample variation, see Jim Tardio's new review of
the Nikon 24-85/2.8-4. He bought three (3) lenses before getting a good
one!!! The first was unsharp at any aperture, the second better but still
inferior to his 28-105/3.5-4.5, and the third one was acceptable.
http://www.jimtardio.com/24-85.html
> rigorous measurements require some rather expensive gear; the usual > amateur tricks like projecting a slide of flat lines on a lens test chart > and measuring divergences from straight lines is problematic - most slide > projector lenses are way worse than the typical zoom or fixed lens ;-(
My method for finding barrel or pincushion distortion is to scan a
negative or slide. I very much doubt that a progressive patch scanner
would introduce linear distortion. It's easy to use photo editing
software to draw a line where distortion is evident. I suppose I could
measure the number of pixels off straight and calculate percent
distortion...
From Nikon MF Mailing List;
Date: Fri, 18 May 2001
From: Randy Holst mistervolvo@home.com
Subject: Re: Just got a F2 .. Meter testing?
laika@sputcorp.com wrote:
[snip]
> Now I'm wondering what you guys > do as far as testing when you get a new body? Everything appears to > be working as it should but I really want to give the meter (DP-1) a > good test to see how accurate it is. I intend to run a roll of Provia > 100F thru it over the weekend and do some bracketing. I'll do some > testing off a gray card and some just from what I consider to be the > scene average. Is there a better way or am I missing anything out?
Hi Laika,
If I'm checking a camera in a store before buying, there are a number of
checks that can be performed very easily. Here are a few critical ones.
1. Mount a 50mm lens on the body and check for proper, consistent
aperture stop down operation when you trip the shutter, at each aperture
setting. Compare the aperture size to what you get when you operate the
DOF lever at the same setting.
2. Check the slow shutter speeds (up to flash sync speed) visually and
by listening to the sound of the shutter. There should be a noticeable
difference between each speed. (Compare it to a know good camera.)
3. Check the fast speeds by attaching a flash to the camera, removing
the lens and opening the camera back. Fire the camera/flash at a white
wall while looking through the back of the camera. At sync speed, the
entire film frame should be completely open when the flash goes off. At
each successive faster speed, more of the film window will be covered by
the closing curtain until only a narrow slit will be open at the fastest
speeds. (This is another test that becomes easier with practice.)
4. Check for shutter bounce. Perform the same test as #3 above, but
removed the flash and aim the camera at a bright light. Firing the
shutter at each speed, check to see if the closing curtain bounces open
a little (very briefly) after closing, allowing a little more exposure
to that part of the film frame. Shutter bounce is bad and will require
a technician to correct it. This also takes some practice to identify.
(All of the above are more important than the meter, since an accurate
meter is worthless without a properly operating shutter.)
5. Check the general accuracy of the meter. If it's clear sunshine
outside at about mid day, aim the camera at the North sky (darkest blue
part, opposite the sun), and take a meter reading. The indication
should be close to the Sunny f-16 rule.
6. Check meter accuracy at lower light levels with an 18% gray card,
against either a known good camera with meter or a hand held meter.
Consistency along the camera's metering range is important.
If all of the above checks out, shoot a test roll of ISO 100 speed
transparency film, using meter readings off an 18% gray card for
accuracy, maybe even bracketing a bit. Take accurate notes and have the
film developed but not mounted, leaving it in a long strip, so you know
for sure which frame is which. Evaluate the exposures on a light box,
comparing the results to your notes. While you're at it, check the
image frames for equal spacing. (On an F2, this should be pretty
consistent.) Also check for any hint of light leaks on the film.
Randy Holst
Boise, Idaho
[Ed. note: chromatic aberration test tips...]
From Nikon Mailing List:
Date: Mon, 16 Apr 2001
From: "L Shepherd" Shepherdlen@btinternet.com
Subject: Re: [NIKON] AFS 28-70 2.8 scratch/quality control issue?
Hi everbody,
I have six AFS lenses and the 2 dedicated converters and all
are fine examples so maybe I have been lucky. The 300 F2.8AFS did arrive
with damage to the lense hood knob. However when I ordered mine Nikon UK
were out of stock and had one shipped over from France to Nikon UK, then
it was shipped to the dealer, who then shipped it to me so I put that down
to a shipping problem. A new hood was promptly supplied.. I had a 105
macro D supplied with a small but obvious defect in the metal barrel and
rejected it, and the black is starting to wear on the back of one aperture
blade on a 35mm f2D after only 4 months so that will go back under
warranty. Also the "new" black mat plastic around the front element of the
18-35 zoom marks very easily, whereas all other Nikpn plastics seem fine.
The same plastic seems to be used on part of the 85 PC.
I know a lot of Canon users who have had quality control problems recently
and Olympus standards dropped over the 25 or so years I used the system.
Perhaps I am lucky in having a 25 year old lens test chart which measures
resolution and astigmatism (if it is present near the centre of the image
there is an off centre element). For those who do not know to test for
chromatic aberration you need black and white film and Wratten filters
25,47B and 58; available relatively cheaply in gelatine form. Set the lens
at about 5.6, focus carefully and shoot using the red (25) filter and then
without ajusting focus shoot through the other 2. If the second or third
negative are not in sharp focus the lense has cromatic aberration. Touch
wood but so far I have never had an opticaly poor Nikon lens. Even so I
only use dealers I trust as, sooner or later, lemons get through.
Len Shepherd.
From Nikon MF Mailing List;
Date: Mon, 16 Apr 2001
From: Steve Bartlett sbartlett19@home.com
Subject: Re: re: variations in glass and lenses is very large/significant
etc.
Andrew,
I'm far from an expert on the subject but I give it a shot. Perhaps
someone more knowledgable will jump in to correct me if a am wrong.
To detect decentered elements take a test shot of a flat object with the
lens wide open. In general, the corners will not be as sharp as the
center but they should be uniformily less sharp. If one of the corners is
significantly less sharp than the other corners that indicates the optical
elements are not perfectly aligned. One or more elements are
"decentered".
I am less sure of what Bjorn means by focus shifts but that won't stop me.
;) On a zoom lens like the AFS 17-35mm that Bjorn was talking about, if
you focus at 5 meters with the zoom set to 17mm, you should be able to
zoom to 35mm and everything at 5 meters should remain in focus. If it
isn't in focus, then the focus has shifted.
Steve
andrew.simboli@dana.com wrote:
> All: > > A recent post contained this quote from Bjorn Rorslett's website: > "it didn't take me long to detect this sample lens > showed severe faults of focus shifts and decentered elements." > > How do you detect these quality control issues when looking at a lens? > > thanks,
From Leica Mailing List;
Date: Fri, 15 Jun 2001
From: S Dimitrov sld@earthlink.net
Subject: Re: [Leica] is it possible for one M lens to misfocus?
On this particular model, I've had two bad lenses. The first had a
helical system that was sloppy and was turned in for salvage, under the
warranty. The second one had a couple of cemented elements separate. One
quick way to check is to see if, when looking trough the rear elements
and tilting the lens side to side, they are concentric circles. But
definitely send it in to the Jersey folks.
Slobodan Dimitrov
...
Date: Sat, 21 Jul 2001
From: dickburk@ix.netcom.com (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Testing sharpness of old extar
Patrick Caldon patc@computer.org wrote:
>I recently got myself a 4x5 speed graphic with a 127mm extar. The lens >looks fine apart from some slight marks and the speed selection ring >being quite stiff; this is freeing up as I'm using it however. > >I've taken a few exposures now, but noticed that the images prouced are >a quite soft and not very contrasty; the few polariods (on 54 -100) I've >done particularly so. I can't get a decent black and decent white out >of the polaroid simulataneously. I have no idea whether the probem is >the lens, the film, or my focussing technique. > >All of this is done at about f/16 -> f32 on a variety of shutter speeds. >Currently I'm using a "make it up as I go along" technique for >focussing, which involves picking an object I particularly want to be in >focus, moving the lens back and forth until it is in focus in the ground >glass, and then stopping down at least until something else in the >foreground is also in focus. > >Is there any good easy quantitiative technque for testing the lens >quality - particularly the focus/softness? My objective is to work out >if I'm causing the problem or if it's the lens. > >Thanks, >Patrick.
Ektars are very sharp lenses and quite consistent form one to
another.
Check the lens itself by shining a flashlight through it. Look for
haze and scratches. Check the surfaces for scratches by shining the
light across the surface. A magnifying glass helps.
Scratches reduce contrast. If there are enough the diffusion they
produce also affects sharpness.
Internal haze can ruin contrast but its easy to remove. You can do
it yourself. If your lens is hazy post back and I will describe how to
get the cell open without mutilating it.
Check the rear component by shining the light through it to see if the
cement is hazy. I've seen this on a few Kodak lenses although its not
common. The synthetic cement they used is generally trouble free but
sometimes develops a haziness or even a slightly orange-peel look. Its
possible to re-cement the lens but the cell must be machined open making
it a job for a professional.
To check for lens performance the easiest thing is simply to examine
the image on the ground glass. Good Ektars should "pop" into focus,
even wide open, there is very little recidual spherical aberration, so
there is no haziness of highlights when wide open. If the lens looks
sharp on the ground glass the image on the film will also be sharp.
If you use the ground glass for focusing make sure that the GG is in
the right position. I struggled mightly with my first Speed Graphic
because I was getting what looked like sharp images on the GG but not
on film. Plus, I couldn't get the rangefinder adjusted.
After changing lenses (the original Tessar turned out to be just
fine) I discovered the GG was not being held in place by the clamps at
the sides of the panel, so was moving around. Ugh! In any case, make
sure the back fits right, and if its a Graflok back, make sure its
complete, meaning the Ektalite field lens isn't missing.
If you use the rangefinder make sure its really aligned and matches
the lens. Check this on the ground glass. The Kalard side mounted
rangefinders may look crude but are actually very accurate when
adjusted properly. If it needs adjustment you will find a rather long
post of mine on the Graflex.org site describing how to do it.
I may add to this since I've just set up three of them in a row and
reminded myself of some things which can save your patience and
temper. They are very tedious to set up but are quite stable once set.
I've discovered some of the causes of instability which may affect
some of these guys.
In short, you have what should be an outstanding lens and should be
getting better results from it, if its not actually damaged.
---
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: stuart_bobb@hp.com (Stuart Bobb) Newsgroups: rec.photo.equipment.35mm Subject: Re: Any tips on testing lens Date: Mon, 01 Oct 2001 > >Check that the diaphragm stops down instantly when the relevant linkage >is operated. Excess oil can affect the operation of the iris diaphragm >blades even before it becomes visible. Good stuff! A few more in this space are: a) Check that the aperture springs back open fully. I've seen lenses where the blades looked fine but after stopping down to f16 or f22 they did not spring 100% back open. b) Make the the blades come in cleanly to form a hexagon (octagon, etc). If some blades don't go in as far as others, the resulting polygon will be oddly shaped. How odd does it need to be before you get problems? I don't know. Two other simple tests. Check the close focus. Does it focus as closely as the specifications for the lens state? Check infinity -- find something that is quite a distance off and make sure that your split image (or whatever focusing aid you have) comes into alignment _before_ you run out of ability to turn the focus barrel. In other words, confirm that infinity is a bit further away than 90 or 100 feet. :-) Look through the lens at a brightly lit white wall. Is the glass giving everything a hue or tint that maybe isn't expected? Stuart
From: Richard Fateman fateman@cs.berkeley.edu> Newsgroups: rec.photo.equipment.medium-format Subject: Re: Feedback on Fuji GS645 folder Date: Wed, 17 Oct 2001 take a small flashlight and hold it inside the camera, point it into all the corners of the bellows. Any light showing means you need new bellows. $100 or more repair, if you can get someone to do it. Some people find the rangefinder too small, viewfinder hard to use with glasses. Somewhat delicate mechanically, excellent optics, great medium format for travel. RJF JessKramer wrote: > Any feedback on the folder with the 75mm lens. Considering one for travel and > street shooting
From Nikon Mailing List: Date: Wed, 14 Nov 2001 From: tpeach@gte.net Subject: Re: Buying Used Lenses --- In NikonMF@y..., "fagun" fagun@h...> wrote: > I live in Bombay, India. So www.keh.com and ebay are beyond my snip>>>>>>> > available is immediately picked up. So all that is normally > available is much abused equipment of which as rookie I don't think > that I am able to coorectly estimate a fair price. I greatly > appreciate the various suggestions given to me and will incorporate > those possible in my search for a good used MF lens. snip>>>>>>> Different markets, different challenge I guess. We may not make a "confident shopper of used Nikon glass" out of you, but here are some of my thoughts on the subject: * Manual focus lenses made by Nikon are remarkably rugged and durable. Some of the cheaper series E lenses had some structural failures, but for the most part the AI and AIS lenses are very strong. * Beat up paint finish on a lens only drives the price of the lens down, it doesn't alter its usability. * Even 'swirl marks' and other minor blemishes on the glass don't have as much affect on the image as many photographers think. If I am offered a beater of a lens at an attractive price, here's what I check for: * Does the lens not have any unusual looseness (e.g., can I make the front lens barrel point slightly off axis)? * Does the lens focus smoothly throughout it's range (no rough spots)? * Is the lens free from fungus (fungus looks like spider webs on the glass, and it can be on the internal elements; you might need a flashlight to check)? * Does the aperture stop down quickly? With the lens off the camera and the aperture set very small (f/16), give the aperture tab on the lens mount a 'flick'. It should cycle very quickly from closed to open to closed again. Compare it to a "known good lens" if you're not sure about this. Also, the aperture blades should not have oil on them. * With the lens on your camera, will it focus at infinity? Will it focus at its minimum marked distance? If you can answer 'yes' to all those questions, the lens is most likely functional. If it has a 'nice price', say quite a bit below www.keh.com "bargain" grade, it's probably worth a test roll of film to find out. (Obviously, your local market may influence your opinion on pricing.) If you're still stuck buying new AF lenses, I'll throw in a vote for the Nikon 35-70 f/2.8 AF or AFD. Not particularly cheap, but well-built, excellent performance optically, and pretty good MF feel as well. Is there anything comparable in say a Tokina ATX for less money that has a good MF feel? -Todd Peach tpeach@gte.net
Date: Fri, 23 Aug 2002 From: ww wardcheese@DIRECTVInternet.com Newsgroups: rec.photo.equipment.medium-format Subject: Re: Bronica S2A - Testing a second hand body (no lens, etc) Tom-- Until I finally saved up enough money to buy my current medium format camera, I survived on the old Bronicas, and they have a very special place in my heart to this day. Anyone who tries to talk them down is simply predjudiced. Do your research, find the right unit, and use the hell out of it! The S2A is rugged as hell, takes a wide range of really wonderful lenses, is entirely battery -free, and no thief worth his salt will bother to steal it. You can get the Nikkor 75mm f2.8 for a song, and the helical also, so don't worry about that. Email me directly and I can help you find one. (use wardcheese@netscape.net rather than the above address.) Backs usually go for a hundred or less too. The most common problem is that the foam light seals will have deteriorated. Light leaks are usually not a problem, but it can leave foam particles all over the innards and it will need a good cleaning. It's also common for the pieces that determine the exact position of the mirror and the exact position of the focus screen to wear slightly, affecting focus. The S2A is more durable than the S2, S, C, and earlier, because they used all steel gearing in the S2A. With the S2A, the only loss was that they didn't put any mirror lock-up. It's loud enough that you won't want to fire it in church, but I always liked the sound. Like slamming a car door. Make sure the shutter fires reliably. Hold it up and look through the body as you fire it at a variety of speeds. You should be able to see a clear hole through the back and out the lens hole when you fire. Make sure the mirror goes all the way clear. The shutter should really slam across the opening with confidence, with no hesitation at all. Hold the camera up at eye level with a bright scene behind the camera, so when you fire the shutter you will see bright light through the body. Looking through the lens opening and straight through the camera, fire the shutter at each speed a couple or three times. At slow speeds (1/4 sec or more) your eyes and ears can tell you whether the speeds are anywhere close. When you get into 1/30, 1/60, etc, it's harder to judge the speed but your eye should still get a very clear square flash through the body. You are looking for any speeds where the curtains are not allowing an even exposure, perhaps one curtain drags a little. It's not too hard to see when one is messed up. You will just see a rectangular flash instead of the full square frame. Make sure both shutter curtains (before and after winding) are in PERFECT shape. Bring a small flashlight and look CLOSELY for pinholes in both curtains. Check the entire mirror for scratches, especially along the bottom edge; people often scratch the lower edge when they install lenses too quickly. Shake it vigorously and turn it upside down and roll it around in your hands. It should NOT rattle. Hopefully, you have done enough research that you know a good price for a body. The whole system, body, finder, back, and 75mm lens, can be found pretty reliably for $400. I found one for $275 and bought it as a backup just because it was TOO cheap. Make sure that the seller is really giving you a deal; I would say that over $200 is a rip off, and $125 - 150 is fair, given you can't test it. (Right now on Ebay, there is a complete S2A system for a "buy it now" price of about $300. Someone has a 75mm Nikkor lens at a starting price of $75 and NOBODY has bid. it ends today.) Again, feel free to email me if you need any more info or halp. --ward ...
From: jge@cs.unc.edu (John Eyles) Newsgroups: rec.photo.equipment.medium-format Subject: Re: An ebay Saint Date: 19 Sep 2002 Yes, the fellow at Camera Wiz suggested shining a flashlite through the lens of my GW690II, with the aperture and shutter wide open, and man, did it look horrible ! I guess this is a pretty standard trick, but I'd never heard of it. And the outer surfaces of the lens looked so pristine when I received it from KEH. He also said this crud I saw (on the interior lens surfaces, as illuminated by the flashlite) was due mainly to the workings of the shutter and diaphragm. The exposure counter is only in the 200's (meaning 2000+ exposures). John > My personal opinion is that it's the result of a > "falling out" of atmospheric particulates from pollution and smoke. > It's probably the number one cause of softness in older lenses, and > it's yet another good reason to spring for a CLA.
From: AC/DCdude17 JerC@prontomail.com Newsgroups: rec.photo.equipment.35mm Subject: Let's inspect our lenses with blue light Date: Wed, 25 Dec 2002 Thought you just cleaned your lens/filter surface just perfectly? You maybe surprised when they're inspected with blue light. Scratches and smears scatters light. Scratches and smears that you couldn't see under ordinary light can be detected under strong blue light since blue light diffracts differently. When you use narrow band blue light, there's no overlapping between different light spectrum and scratches and smears are pronounced much clearer. Shine blue light at negatives or perfect looking CDs from different angles and you'll see microscratches you don't usually see. Thought I'd share that blue LED Photon Micro's are useful for purposes beyond raving.
From: SB beefybeers@hotmail.com Newsgroups: rec.photo.equipment.medium-format Subject: How do I go about testing a used MF camera? Date: Tue, 11 Feb 2003 Some things I have heard I should try: - Shoot with no viewfinder on or film in so as to see the mirror assembly move correctly. - Shoot a roll of slow color slide film (slow and slide were very much stressed), at a single subject, on a tripod, at different shutter speeds/apertures so as to see that the lens works correctly at all speeds and apertures. The roll should be consistently exposed throughout the entire sequence. Slide film supposedly has a more standardized, and less lab-technician affected outcome - meaning they don't try to make the slides look fantastic as they would try to do for prints. This also checks for light leaks in the film carriers. Things I am concerned about : - How do I check the shutters on my lenses? How can I move them around so that I see they move correctly and smoothly, and don't have oil on them? - Should I just immediately take my camera to a shop and have it cleaned? Thanks ahead of time! Shane
From: "Art Begun" beguna@mindspring.com Newsgroups: rec.photo.equipment.medium-format Subject: Re: How do I go about testing a used MF camera? Date: Tue, 11 Feb 2003 Inspect the inside of lenses with small flashlight. Look for scratches and fungus, oil on blades, and fire at different speeds to make sure it seems to work. Note that you have to have the lens cocked to mount it if I remember correctly. Use fast film to check for light leaks. Don't forget to check flash sync.
From: john@stafford.net (J Stafford) Newsgroups: rec.photo.equipment.medium-format Subject: Re: How do I go about testing a used MF camera? Date: Tue, 11 Feb 2003 The best test of a shutter is to pick a plain subject like a wall in even shadow or a clear sky. Throw it out of focus. Shoot a roll if pictures with F-stops equivalent to shutter speeds (you know, 1/500 F2.8, 1/250 F4, 1/125 F5.6, 1/60 F8, 1/30 F11, etc.) Look at the negatives (or transparencies) - not prints! You are looking for consistent exposures from frame to frame. (It's unlikely the F-Stops are off, but it will be very obvious of it sticks.) Do another roll with several objects in focus, beginning at minimum distance with the lens WIDE open, high shutter speed. You are looking for focusing errors. Look through the lens(es) with a bright light, like a mini-torch. You are looking for fungus (looks like a spider web parts) and fogginess. Look for oil on the shutter blades. It should not have puddled. Do the same for the finder. If it's battery-powered, make sure you can still get the batteries. If you have to resort to mercury batteries, pass. Shake the hell out of it. No rattle? Really? Most of 'em rattle! :)
From: Helge Gundersen helge.gundersen@chello.no Newsgroups: rec.photo.equipment.35mm Subject: Re: Used Lenses, what do you look out for? Date: Mon, 07 Jul 2003 Here's an article dealing with this: http://www.epinions.com/content_1552720004 -- Helge Michael Bain mike-usenet-1001@macboy.homeip.net wrote: > I'm thinking about buying some used lenses as a way of getting the gear > I *want* for a price I can afford. I realize used equipment is a > crapshoot, but what are the big things you want to watch out for in a > used lens? I've heard about fungus, and I'm assuming cracks or chips > aren't good either. What does normal wear-and-tear on a lens look like, > and what are signs of damage or abuse?
From: "Chris Barnard" lord_waymaster@yahoo.com Newsgroups: rec.photo.equipment.35mm Subject: Re: How to buy second hand lenses Date: Tue, 20 Jan 2004 I generally just have a look through the lens at full aperture into a bulb light from both sides, looking for dirt and, more importantly, fungus. Try focus on each the elements within the lens one by one. If there's any fungus then leave it unless you're getting a *really good* bargain - offer to take it off their hands for some incredibly low figure and then see how bad a few shots develop. I have a habit of taking lenses apart if there is something wrong with them - fungus is especially difficult to get rid of (most of the time impossible), but you can stop it spreading so if the fungus is only at the edges or its relatively light, then I'd be prepared to pay a few quid for a lens if it would be worth a lot more without the fungus. Wear marks on the barrel are a good bartering point, also check that the focusing ring turns all the way without stiffening up - the same goes for zoom if it has that function. Of course, as you stated, you should also look for play in the front element - although a little bit isn't anything to worry about. Again, stiff focusing rings or play in the front element can be cured by taking the lens apart and it can be relatively easy to sort out with a bit of common sense and a lot of care. Give the lens a shake as well. Might be full of grit or sand - try shaking it about and then turning the focusing ring again. I had a lens with sand floating about in it - occasionally it would get in part of the one-touch focus/zoom mechanism and start making horrible grating noises. Another shake and it would all come loose, but you can imagine the wear it might cause. Finally, just have a really good idea of what it is you're buying. Manufacturers have often produced different lens designs with the same focal lenses - some are bad and some are good. There can be also some subtle and not-so-subtle differences between buying a brilliant quality, expensive old lens and just an OK one. Eg, if you have your eye on a Carl Zeiss, is it a Sonnar or Jena (or whatever)? So, do your research!!! If you get ripped off, it'll only be your fault ;) Chris. ...
From: "Jeremy" jeremy@nospam.thanks.com Newsgroups: rec.photo.equipment.35mm Subject: Re: How to buy second hand lenses Date: Tue, 20 Jan 2004 "Nick Zentena" zentena@hophead.dyndns.org wrote > Try all the controls. Does the focus ring move easily? Does the aperture > change? How does it feel? I would add to that the following: 1: Lenses that have dings on the filter ring may have been dropped, and the internal alignment of the elements may have been adversely affected. I decline purchasing such lenses. 2: Shine a flashlight through the lens while looking through the other end. Dust particles are not a problem but you will better see any fungus, cracked elements etc. 3: I decline purchasing lenses with tight focusing rings, slow apertures or oil on the aperture blades. These lenses are only going to get worse, and I don't know how to disassemble them and repair them. The cost of cleaning and lubing them, added to the price to purchase the lens, will probably exceed the price of a lens that does not require repairs. 4: Some lenses, especially those purchased from amateurs, have seen very little use and are as good as new. Check the barrel for excessive wear or brassing as an indicator of how much use the lens has seen. I have purchased used lenses--20 years old--that looked as though they just came out of the box. 5: Have the right attitude. Used gear sometimes is junk, or almost junk. No one gets perfect equipment every time. Sooner or later you will get stuck. That's why the price is so much less than for unused equipment, with a manufacturer's guarantee.