I used to own the older Tamron 90/2.5 (old 49mm filter version; stolen earlier this year) and replaced it with the Pentax M 85/2. My wife owns the the Pentax M 100/2.8 (non-macro) which is essentially the same as the A 100/2.8. I never handled the FA 100/3.5. You ask about the application of these lenses for portrait use. With respect to the optics I can only report the best of the Tamron 90/2.5 for portrait application. Sure there is some flare problem, but for the types of portraits I do, this was not a problem. The problems I had with this lens were in the handling department. This lens is about twice as heavy as the M 100/2.8 and M 85/2.0. I use(d) them with a MZ-5n. The Pentax lenses are clearly better balanced on this body, at least for my tastes. The biggest problem however is the steep focusing ring. I want to use a portrait lens wide open with narrow selective focusing. The Tamron just goes to quickly over the point of right focus. I expect the FA 100/3.5 to be the same and a lens focusing down to life size way worse. (Forget about auto focus in portrait applications.) The Pentax lenses handle way better. They balance better on a MZ-5n and the focus is fine. I can easily focus on the leading eye of the sitter. I like available light shooting, the 2.5 aperture of the Tamron is an advantage over the 100/2.8. I would call the 3.5 of the 100/3.5 a clear negative point. For sure the 85/2.0 is the fastest of the lenses I own(ed). I got it quite resently, and I got some nice portraits by now, but I am still in the testing phase. My wife and me shoot some photos side by side with the 100 and the 90. The outcome showed more of a difference then I ever imagined. I suggest you consider the differences in perspective as well. My personal bottom line: If you want the lens for portrait applications, forget anything with a macro focusing. The handling is to much of a compromise. Hope this is helpful - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
