Originally posted by tibbitts I only have the 16-85. I have the fifth copy I tried and am still not fully happy with it.
Oh My, aren't you Mr. Persistent? That's insane that you didn't get one you liked.
Originally posted by tibbitts I have the 17-50 Tamron and it (and another copy I tried) both lost communications with my bodies frequently. Amazingly, Tamron fixed mine under warranty on the second try! Seriously I think that's very good. But they can't fix the AF, which is just inconsistent across the focal length range at larger apertures - it's just not accurate enough. Plus the focus field curvature also affects performance at larger apertures.
I once did a test shoot with it where it didn't nail the focus in 20 tries. The next day it was fine. Yet, my wife loves it. It's never behaved for her as it did for me. Maybe it just likes K-5s and doesn't like K-3s.
I always wonder about these lenses that were designed for lower MP and slower AF systems.
---------- Post added 03-31-20 at 11:15 AM ----------
Originally posted by biz-engineer Really? I thought the depth of field varies by the square of the focal length, meaning I can use my 15-30 @ 15mm f3.2 and get all in focus frame and enjoy the lower ISO thank to opening up the lens aperture to f3.2
But the lens will still be sharpest at ƒ5.6 and better edge to edge at ƒ8. It's a personal decision to compromise that not all of us will accept.
I get lower ISO by using a tripod in most circumstances.
These tend to be philosophical decisions, not practical ones.
That being said, if you're happy with the results, then it's all good.
Sometimes you do things because you have to, other times you make the choice that suits your philosophy. Most of us don't even check to see what the trade offs might be, or even if there are any. But I think most photographers shoot just under the diffraction limit, there aren't many lenses where that is ƒ 3.2.