Choyin 寫:
OK here is the revised procedure, For better understanding, I have also disemmble my istDL for study:
1. Remove the blue marked area of the mount.
2. Remove the thin metal (M42 stopper) on the 2nd layer ring beneath the mount
3. Sand away 0.2mm of thickness of the metal mount
4. Cut away the plastic screw support.
But I have found a minor difficulty which dosen't matter on the modication. There is a welded wire connected to the tin metal ring with the M42 stopper. did you cut it off or there is no such thing in K100D?
I have attempted to refine the workflow as follows -
1. Remove the blue marked area of the mount.
2. Remove the thin metal (M42 stopper) on the 2nd layer ring beneath the mount.
3. Re-fix the mount to the camera body. Put on the C/Y lenses and shoot at infinity to check if the register is correct. (From my experience, P85/1.4 should be the best to perform the test as it requires highest accuracy in getting a picture of superb quality)
4. If infinity focus is okay - Congratuation! Your Pentax DSLR is now ready for C/Y lenses.
If a blurred picture is got when focusing at infinity - go to step 5.
5. Unscrew the mount again and sand away a considerable thickness of the metal mount. A unit of 0.1mm or so is recommended as a extremely small difference in the register would be able to cause a huge difference.
6. Cut away a thin layer of the plastic screw support on the camera body which is equal to the thickness of the metal mount being sanded away in step 5. Also removed a circle of the plastic (of the same thickness) immediately beneath the thin metal (M42 stopper). If this circle of plastic is not removed, there will not be any difference in the register even the metal mount and the screw support is modified.
7. Re-fix the mount again and test if focus at infinity is okay now. Repeat step 5 and 6 if necessary.
As for the welded wire connected to the tin metal ring with the M42 stopper, I had accidentally cut it off but there is no effect on the camera. But as pointed out by vincenthoy28, ist DL will lost AF function if the wire is disconnected. Maybe the difference is due to design variations between the two models.