Lens Hacker Hall of Fame - Classic Bronica Medium Format Camera Chapter

Bronica Lens Hacking Adapters - 4/14/98
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Date: Tue, 14 Apr 1998
From: Greg Erker erker@sask.trlabs.ca
To: Robert Monaghan rmonagha@post.cis.smu.edu
Subject: Bronica lens hackers please read this

Just posting the following to rec.mf and marketplace. Though you might be interested. Perhaps you would want to place this on your web page as a service to Bronica lens hackers. I won't be making any money off of this though my brother-in-law may make a few bucks for his trouble.

I have a Bronica S2A and my brother-in-law (a machinist) is going to make me a couple of adapters that fit on the 57x1mm threaded mount in the focusing helical.

He would be willing to make extras so I am looking for an expression of interest. Read the following and email me if you would like the #1, #2 or both adapters

These would work on all Bronicas with the 57x1mm mount: S2, S2A, C, EC and EC-TL. Perhaps others also.

1) Metal disk that threads into the 57x1 thread. Would probably have a small hole in the center that you would enlarge to mount some other lens (leaf shutter lens, fish eye thingy that you put in a door etc). Would probably be made from aluminum about 1/4" thick and would be milled down in the center cap area to be about 60 thou thick. Cost would be $10 US plus $2.50 for postage in USA/Canada. Higher postage costs elsewhere.

2) Male to male adapter for mounting lenses in reverse (for macro use). This will be a short thin tube with 57x1mm threads on one end and 58x0.75mm threads on the other. You could mount a 35mm camera lens that has a 58mm filter thread in reverse onto the Bronica. To use your 50 mm lens that has a 49mm filter thread (say) you would buy a 49-58mm step up ring and then mount the lens to the M to M adapter. Material will probably be aluminum also. Cost would be $10 US plus $2.50 for postage in USA/Canada

Note: these won't be a finished product with black anodizing or paint on them. They will be just bare metal adapters for you to play with and finish however you want. Also, I can't guarantee these will be made. But if there is enough interest I think they will. If they are made I will require prepayment in the form of a US$ money order before shipping. Check my ebay feedback rating for an indication of my trustworthyness if you have any concerns.

The ULTIMATE lens hacker is my friend Herwig Zorkendorfer. He can adapt anything to fit anything. He even makes an adapter to put Rollei lenses from their 6000 series medium format cameras onto Canon EOS cameras and maintain automatic diaphragm!!!!!!!!!!

In honor of lens hackers everywhere I just completed a fine quality (gross hack) lens retrofit for a Bronica S. The lens I used is an Angenieux type Y2 135mm f/3.5. It was in an Exakta mount. I bought it for about $7.00 out of a junk box at National Camera in Minneapolis. I'd seen these lenses before in Arriflex mounts for 35mm motion picture cameras and (I think) in a standard mount for Bolex 16mm as the longer tele. I remember them as very sharp on those formats (and small enough in diameter to fit in the Bolex turret mount. They are screwed into their helical mounts and are easy to remove and remount elsewhere

WARNING: French lenses have tricky mounts and hidden screws. This one had a set screw holding the lens in under a cover screw.

The lens covers 6 X 6 nicely with room to spare and is breathtakingly sharp. It works shifted or tilted on a bellows as well.

Now for a "Don't try this at home " trick. I didn't have a 57mm X 1mm ring for the Bronica camera alternative (screw) mount. I had sold my lathe as I found out I am a terrible machinist. The tooling shop I use was quite busy and I wanted it right away. To make a threaded blank I molded one from epoxy putty, using the inside threads of my Bronica c-d extension ring as a pattern.

Note: I had to make two to get a good one. The following procedure is how I made the second one:

Cut a piece of light aluminum plate or similar material for a molding base to a comfortable size more than the diameter of the ring and blank. Coat it with silicone grease and wipe the grease down to a thin film.

Meticulously clean the threads and inside of the ring, finishing with a light solvent. Thoroughly coat the threads and the interior of the ring with Vaseline (petroleum jelly). You can use silicone grease ( it works better than Vaseline as a mold release) but it will be harder to remove the last traces of it later. Set the ring, inside-thread-end flange down in the center of the plate. The grease will make it stick slightly.

Mix about 1/3, or slightly more, of a stick of aluminum-filled epoxy putty until there are no remaining streaks. This stuff starts to set in 2 to 3 minutes so the next step needs do-diligence.

While holding the ring in firm contact with the base plate, push the ball of putty firmly flat into the inside threads. As you press it into the threads the excess grease will be forced up and around the putty. Use care that you fill the threads well and make as even a "puck" as you can; It'll help a lot later. The amount of putty recommended will fill the center of the ring a bit deeper than the threads. DON'T PANIC - ITS OK! Let the mass (mess) sit undisturbed for a few minutes while you rush to clean your fingers because YOU FORGOT TO PUT ON YOUR LATEX GLOVES! (Soap and warm water scrubbing seems to work fairly well on uncured epoxy).

Within 3 to 7 minutes the mass should have hardened to the point where you can just dent it with a firm press of a fingernail. When this occurs, GENTLY unscrew the ring (counter clockwise) while holding the puck in firm contact with the plate. This action will cut additional threads in the rest of the blank. Completely unscrew and remove the ring from the mess. (You need the extra threads as selvage.) The thing will look awful!

Clean up the mess on the extension ring.

Let The blank sit undisturbed for a day or more. It'll harden good and you will have time to get over being depressed over the mess you made.

When you return after it is hard, inspect it for trueness and quality of threads. A few poor quality threads are OK as long as they don't deviate from true. Sand, grind or cut (all three works for me) the messy top section flat to create a blank of uniform thickness. (Measure its thickness on several sides. You want only one starting point for the threads.) Clean the blank with paint thinner after gently prying it from the base plate (if it hasn't fallen off by now). If you proceed carefully, using a mike or good caliper, you will get a blank that, when try-fit, will screw on easily the first time. Lightly sand both flat surfaces with a fine grit, being careful to maintain parallelism, to remove any traces of silicone

Find a center and drill it for your lens or flange. A sharp Forstner bit works well for this.

A little flat black lacquer will dress it.

Mount your target lens and do a test shoot.

Hint: Screwing it into one of the extension rings will usually help get the lens out to infinity.

Afterwards: I would not like to do this trick often. It works OK but is a bit scary. I wish I could get a couple of those screw on body caps talked about on the Web.