My 2.8/300mm
L is ready!
I managed to turn it into a crippled K-mount, so now I can focus wide open and meter with the green button. Or I can just shoot wide open in AV.
The hardest part of the conversion was getting the aperture ring to work. I ended up using the existing parts of the FD-mount. I just bypassed the original (complex) mechanism and attached the arm that closes the aperture inside the lens straight to the aperture ring with a couple of small screws. I had to file some parts of the aperture mechanism down a bit to get them to move without binding and this resulted in wrong aperture ring index markings in the wide end. F2.8 is correct but the actual F4 can be found from the aperture ring position F5.6
There was an aperture lever very much like the one in K-mount lenses already present. I had to remove one spring and shorten and bend it a bit it to get it to work like in the K-mount. And then I had to attach the chinese M42-PK adapter to the lens in such a position that the lever would be in the right spot when mounted on the camera. I used the existing holes in the lens and attached the K-mount with three screws. This resulted in the aperture ring index (and the drop-in filter slot) to be at 9 o'clock position (viewed from behind the camera) which IMO is actually better than under the flash housing.
Infinity focus was easy to achieve after removing the breech-lock parts. There is a focus limiter with a hand screw so I could (and can) adjust the infinity point without shims etc.
After some test shots I can say that sharpness even wide open is very good there is
no CA and contrast is OK (not great, but easy to correct). And what surprised me the most was that I could hand-hold and track and get even a few sharp shots of flying birds. Even though the lens together with my K200D weighs approx 3.5kgs.
Here's a few 100% crops:
Will post more shots (hopefully) soon.