Kenern Petersen , Aug 18, 2002; 07:38 p.m.
Hello, I have several 135mm lenses; a Takumar 2.5, Sears 2.8, and a Vivitar 2.8. I borrowed a SMC Pentax 135 3.5 about two months ago and shot a test roll of Agfa Precisa 100 to see if I could tell a difference using an 8x (inexpensive) loupe. I have been seeing many SMC 135s going for 28-35 Euros in my area of Holland and considered buying one. I too wanted to get rid of the lesser quality. Right away you would think the Takumar and SMC would blow away the Sears and Vivitar--not so.
I shot each lens from a tripod using my A3000 (center-weighted metered) body at a colorful box (lots of text) using the widest aperture, then smallest and then two stops from widest. At the two stops from widest, I cannot tell a single difference in the quality of the slides. Only at the widest aperture is there a noticeable difference with the SMC leading. The Sears was actually better than the Takumar on the widest setting followed by the Takumar, and then Vivitar. On the smallest aperture all slides looked identical except the Vivitar (photgraphed text not sharp).
After considering the results, I did not buy the SMC 3.5. For my needs, the Takumar will do. As for the other lenses, I'll get rid of the Vivitar and hold on to the Sears at least until I get to try a SMC 2.5.
If you have been shopping for PK lenses, you know that there are over a dozen different 135mm brands out there, especially in Europe. Most are all 2.8s. The 2.5s are the most expensive regardless of brand, and at least in Holland the 3.5 SMC are the cheapest, even cheaper than a Petri or Pallas 2.8. The odd brand M42 screw mounts are practically used for paperweights now.
Your two lenses are very similar in build quality and in the slides they produce (my tests). You might want to shoot some 100 speed negative film have it developed and printed by a quality lab and judge the results yourself, or shoot slides and let a knowlegeable person evaluate them with a real quality loupe. Don't let the evaulater know from which lens they are from until he points out the flaws (some people are biased against the Takumar right away.) Hope this helps.