OOOPS! My 1.4/50 Auto Yashinon and Spotmatic don't mate!!

[eumenius]

Hi friends,

today I got in a strange situation In our used camera store I noticed a M42 lens, 1.4/50 Auto Yashinon-DX - used but not abused, excellent clean glass without a sinle mark, perfectly working diaphragm etc. I bought it, planning to use with my Spotmatic SP... imagine my face, when I put both together and saw that the back element of Yashinon on some distances protrudes too deeply into camera, obstructing the mirror path! I was really impressed... was there a special M42 body with smaller (??) mirror or working distance to use this lens? I think that this Yashinon is a rare and very good lens, but I can't find an application for it, if it doesn't fit my faithful Spotmatic. What should I do with it?

Cheers,
yours stupid PhD Zhenya from Moscow

 

[Donald Qualls]

I presume you're encountering this at or near infinity focus setting, when the optics will be closest to the film? Does the lens in fact focus to infinity, or does it go "past" infinity a bit, suggesting that the Yashica it was originally made to fit might have used a subtly different mount (same threads, different reference distance)? I seem to recall the Yashica SLRs as being M42, though.

The other possibility is indeed that the Yashica SLR might have had a smaller mirror; I'd guess you only have a millimeter or so of actual interference at closest setting, and since few SLRs have 100% ground glass, Yashica might well have accepted a millimeter of vignette on image top (mirror bottom) in order to clear a lens with more protrusion.

Still another possibility -- either your Auto Yashinon or your Spotmatic SP is a hair out of adjustment. But I'd guess the first place to look would be the infinity stop in the lens.