Someone earlier recommended a Pentax 50mm f1.4 Takumar for the Zenit. Be VERY careful if you want to use this particular lens. I have the SMC version (the one with the extra pins/lugs on the back to support the full aperture metering on the SPF and ESII), and when I put it on my Zenit, the lens jammed and would not come off (a loud metallic 'clunk' when the lens was about 2/3 unscrewed). After about twenty minutes of pulling/pushing while unscrewing the lens, it somehow popped off, but I don't ever want to go through that again. OTOH, my 120 and 200mm Takumars and my 28mm Asanuma work with no problems, so it is, perhaps, the fact that the 50mm 1.4's rear element and surrounding metal stick out farther than on any other lenses I have. Just a thought....