Pentax Digital

A lot is going on about these lenses, because Ricoh shared an almost equal mount with Pentax in the film days.

However, it does not mean that they are the same!

There are different variations of the mount, and I do not know all of them, but I can tell you what I do know:

1. XR mount: this was the original bayonet mount from ricoh, and is basicly the same as the K mount. An XR mount lens will fit on your Pentax DSLR without problems.
2. P/KA-R or R-P/K or any other variant of this name (do not confuse with Konica Auto Reflex mount, K-Ar! (thanks Bigdawg, for clearing this up)): this mount is similar to the KA mount Pentax made, but (!!!), it is not fully compatible! Some versions are, some are not.
   • First off, some PK/AR lenses have a small golden pin on the mount, which is not supposed to be there. This pin will get stuck in the AF-contact when you mount it on a DSLR! So this type is not compatible with Pentax DSLRs.
   • Sometimes the extra contact is not a pin, but a small ball. I’ve been told that this type does not get stuck on the camera. I had a Tokina SZ-X lens in this mount, and it worked like a KA lens. So this type is compatible.
   • Another frequent problem with Ricoh mount lenses, especially the ones from third party manufacturers like Vivitar and Sears, is that the flange protecting the aperture lever is too large. This way you cannot turn the lens into position when trying to mount it on the camera.

Solutions:

• for the pin-problem: if you dismantle the lens mount, you can easily remove the pin, and the lens will work. This does require a steady hand, and the skill to put the lens back together though…
• edit: another solution for the pin problem: Appearantly it is possible to grind the pin off with a dremel tool, while protecting the glass with a rear lens cap. This method might be easier if you’d rather not dismantle the lens. (thanks Darren for this solution)
• for the flange problem: If the lens does not suffer from the above mentioned pin-problem, there is an easy solution for this, you can just cut or grind a piece of the flange off. Be careful not to damage the lens elements though (or yourself, for that matter…)
• edit: another solution for the flange problem: the flange can be removed by undoing 2 or 3 screws. The internal baffle comes out as well.

Illustrations:

The left one, a Vivitar 28-200mm f3.5, had the flange problem, the right one, a Tokina SZ-X 70-210mm, had no problems.

Neither had the pin problem, but instead had a ball where the pin usually is.
Notice the naming of the mount on the Vivitar lens.

A closer look. Notice the huge flange on the Vivitar lens. You can grind this down to make the lens work.

This entry was posted on Friday, August 24th, 2007 at 4:53 pm and is filed under technical stuff, lenses. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.