Adjusting the I-61L/D in LTM for the Leica

[Brian]

At start, the RF cam is off and the actual focus is off. The RF cam shows 7m for a 5m target, and the actual focus is just over 4.

Distance off should be 5m,

http://www.ziforums.com/picture.php?albumid=263&pictureid=2935

And the Shim is off for the Leica.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2936

[Brian]

Remove the Light Baffle, just like on the I-50 that was the subject of another project.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2937

The optics module is held in by this retaining ring and one set screw.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2938

http://www.ziforums.com/picture.php?albumid=263&pictureid=2939

It's the really long one! It's typically near the one nearest infinity mark. 1 of 3. Just like Let's Make a Deal.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2940

[Brian]

With the retaining screw out, the optics module comes out easily. This one is going back into the LTM mount, and needs to be shimmed. This one needs about 0.1mm so that the distance scale lines up with the actual focus.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2941

I started with some Shimming material, cut some rough shapes. Because of the retaining screw, I use split shims. Pieces lined up on each side of the optics module. Press the metal into position to get an imprint, and then cut it so it fits into the ledge.

When re-assembling, you need to make sure the shims are in position, and the optics module holds them in place as you tighten the retaining ring. On this one, I put the retaining screw in first to hold it down. Then, tightened the retaining ring. After that, I took the set screw out, finished tightening the ring, tapped a new hole for the set screw, and put it back in.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2942

Focus is now close to the actual measured distance.

[Brian]

I could have shimmed the optics to match the RF cam, and let the distance scale error stay. BUT- that meant not being able to focus to infinity. The RF cam also needs to be "shimmed". I used copper tape. Again, cut a rough shape and press it onto the Cam to get an imprint. Cut a strip of tape. On this one, I used a very small amount of super-glue on the Cam and pressed the copper tape onto it. I used a metal pin to place the glue. Holds better than the copper tape alone.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2943

With the strip of copper tape in place, very close agreement with the distance scale and actual focus. A little room for infinity focus on this one. At F2.8, plenty close.

http://www.ziforums.com/picture.php?albumid=263&pictureid=2944