Lately I have found my 50mm Tak not so sharp - in good light it would require stopping down to f/5,6 to get tack sharp images, compared to the Pentax-M 50mm f/1,7, which I can use at f/2,8 while maintaining the desired sharpness. At f/1,4, the Takumar is so soft I can barely see any use for it. Last night I did an A-B test between the Tak and a Helios 44M and got the following results:
- both at f/2 (Helios wide open), the Helios is noticeably sharper
- the 8mm more in focal length are noticeable too
- the yellowing seems to affect color balance only, but not the transmittance of the lens (the pictures look exposed the same, at f/2, 1/60 and ISO 1600)