A few days back, I got a wonderful Tokina 24-40/2.8 ATX but with OLYMPUS OM mount.

My Hypothesis was that since Tokina built lenses for many brands the elements must be common to all; and thus mount should be interchangeable without much trouble. All I needed was a donor lens for the mount and extra pieces that maybe different. A cheap RMC28-80 was found and my first attempt:

CHANGE OF MOUNT

The actors: Tokina ATX 24-40/2.8 as star and a Tokina RMC 28-80 as donor. The mounts seem similar, screws in the same place; inner cover in the same place, etc.

After removal of the first screws I could see that the aperture index lever was located in different places; but there was a simple way to move that since the inner elements had screw holes in the positions for most brands.

The only unsolved problem so far is the spring that keeps the diaphragm open. In PK opens anti-clockwise and in OM in the other direction. I'll have to make a deeper surgery to switch the spring side.

I checked in a ProgramA camera; and it underexposed a lot; due to the action of the index lever AND the closed diaphragm. This was expected so I was happy.

However, for a DSLR the lens is well usable; since it acts like a SMC Takumar in Manual position; where you can see the diaphgram closing all the time.

TESTS