Quote Originally Posted by lens_hacker View Post
If the Summicron that came with the camera is original to it, check the glass for yellowing. Summicrons with a SN earlier than about 105xxxx used Thorium. It tends to yellow the glass, but can be sun-bleached out. If you do this, you might also need to relube it. Or just use with B&W and skip the yellow filter!
Since posting this, I've tried using a UV light to bleach some of the yellowing out of a Pentax 50/1.4. It looked like it had a positive effect, and does not produce the heat by-product of direct sunlight. Kind of makes sense as Optical Glass absorbs deep UV, and that may be the portion of the spectrum that is doing the trick.

Also- the Canon 50/1.5 in LTM is a bit smaller than a J-3. Fits in the Pouch case of a CL, and does not block the viewfinder of the IIIf.