the OP, and others, might want to look at the submissions to this thread:
https://www.pentaxforums.com/forums/26-mini-challenges-games-photo-stories/3...ml#post3788074
and look at what equipment was used by the photographers to help narrow down what lenses might be useful
warning: there are a lot photos to look at
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Originally posted by MetteHHH So, I have a 100mm D-FA macro f2.8. When I first got it, it suffered badly from sticky aperture blades, I got excellent advice here on the forums, apparently it is a known problem with this lens, and I sent it in for service. Since then it does stop down to some degree, but not fully - past f7.1 or so pictures tend to be overexposed, and the problem is worse if it has been sitting in my camera bag for a while. I guess the aperture blades are still not as freely moving as they should be. . . .
first of my question - where and when did you send it in for repair?
second why not send it back and ask them why the repairs did not solve the problem if the problem became apparent shortly after it was return to you ?
I have had zero problem ( knock on wood ) with my copy of the DFA 100mm F2.8 Macro and other than the usual " operator error " all of my equipment suffers from, I am quite please with the results. it has an excellent reputation.
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Originally posted by wanderer2 :
" Do all four of the 100mm f2.8 autofocus macro models have this sticky aperture blades problem, the F, FA, and two DFA models (WR and non WR)? My understanding is that the optics are the same in all 4. I've been considering purchasing one, possibly an F, and would like to avoid sticky aperture blades if possible. "
the optics are shared with the following versions of the Pentax 100mms according to this In Depth Review
" Pentax-D FA 100mm F2.8 WR Macro Review
Specifications
The lens covers the full 24x36mm format, not just APS-C. The aperture blades are rounded, delivering a smoother bokeh which is important for a macro lens. However, unlike its predecessor, it has no aperture ring.
The optical design is the tried-and-proven formula of the previous generation D FA 100mm F2.8 Macro lens, which in turn had inherited the optical design from the well-respected FA 100mm F2.8 and F 100mm F2.8 macro lenses introduced in 1991 and 1987, respectively. None of these earlier lenses had rounded aperture blades.
Read more at: Pentax-D FA 100mm F2.8 WR Macro Review - Specifications | PentaxForums.com Reviews
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" sticky aperture blades " is something that can commonly occur with older lenses as far as I know.
Sticky aperture blades?
https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/232275-...ml#post2459384
I have had no problems with any of my vintage lenses.