Since a Pentax K-mount FF has been rather pessimistic for long and even that the K-mount might be aborted, today I have decided to build my own K-mount Full Frame body myself again, to accommodate my superior and excellent FA*85/1.4 lens, which has been collecting dust for long without a matching FF body!
So, here we go!
Warning: If you follow me to do the following, do it at YOUR OWN RISK!
And, great care must always be taken throughout the whole course:-
1. Put a large white paper on the working desk/table with bright illumination on it;
2. Find a high quality matching-size screwdriver for opening the rear of the lens;
3. Remove the three screws *around* the mount so as to pick out the whole assembly of the aperture coupler protector, as follows:-
4. Remove the five screws *on* the mount for dismantling the mount. Before doing that, do put on adhesive tape onto the gold plated electrical pins and contacts to prevent them from dropping off when the mount is removed:-
5. Pick out the aperture ring coupling ring inside:-
6. Unscrew the aperture coupler and remove it:-
7. Put back the aperture coupling ring and the mount:-
8. Get a quality Pentax-K to Canon-EOS adaptor and put it onto the K-mount lens. Mine is a Kipon adaptor with a programmable chipset and PCB attached:-
9. Keep and store the removed parts safely and properly:-
10. Focus adjust the lens before use, the correction parameter can be either entered into the body or into the memory of the programmable chip of the adaptor, which I choose the latter. This calibration method of mine is used.
Last but not least, other K-mount lenses could also be mounted!
Related:-
Compatibility List of Some Pentax Full Frame Lenses on Canon 5D Body
Compatibility of DA Lenses on Full Frame
K-5D Mark III: DA 18-55 II Converted to a 24-80 FULL FRAME Lens!
When the Focusing Screen Lies - Part 2