Why some f2.8 shots are OK and some are soft/out of focus?

Started Nov 12, 2012 | Discussions thread
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Why some f2.8 shots are OK and some are soft/out of focus?
Nov 12, 2012

Finally we got some sunshine :), and I got a chance  to test my new-old Tamron 70-200mm/2.8 under good light. This is my third outing and still trying to learn it's tricks/limitations.

The lens seams to be doing good at f4, at all distances,  but  I'm getting mixed results at f2.8.

At f2.8 it tend to get soft, specially at distance. It seams to be a lens-limitation, but it's hit and miss with no consistency. I'm trying to experiment and find a workaround, and I hope you guys can help with good C&C too.

All shots are with tripod, a fast PP, and no crop, except the last shot (I didn't crop to preserve the sense of distance, since distance, in case it's playing a role in focusing at f2.8).

f2.8 at normal distance. It tend to produce more soft Images.

f2.8 at normal distance, with the same issue as above.

f2.8 at close hold, and it looks Ok to me.

f4 at normal distance, it tend to be ok under good light.

f4 at normal distance, and it's as above.

f4 at close hold, and it looks OK.

f8 at distance, almost 100% crop

Why some shots are OK and some are soft at the same aperture?

Why the distance is playing a opposite role? If it was a focus inaccuracy. focus-miss, one would expect it to be more visible at close hold, but this softness is more visible at distance. Is distance play a role but different ? C&C is welcome.

 Sam_Oslo's gear list:Sam_Oslo's gear list
Sony SLT-A77 Sony 50mm F1.4 Sony 20mm F2.8 Tamron SP AF 90mm F/2.8 Di Macro +2 more
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