Unfortunately a few candidates are being missed...
Personally I think this is Pentax's sharpest AF lens: the
FA* 200/4 Macro - 100% crop - no sharpening.
Great Spangled Fritillary:
As is this lens -
the FA* 300/2.8 -
sharp across the frame even at F/2.8. The subject is 6 feet away, only 7-9cm long, at 1/160 second in overcast, windy conditions with a 300mm + 1.4x TC (420mm) in the mix..
Again, 100% crop, no sharpening.
Ruby Throated Hummingbird (male):
Another male Ruby Throated Hummingbird. Same lens and TC used as in #2... However, this was
taken at only 1/100 sec., 420mm, again no sharpening (just ACR default conversion settings from RAW):
Same lens with K10D,
no sharpening, 100% crop, ISO 800, no NR, 1/60 second:
One more lens -
the FA* 250-600/5.6 is quite sharp as zooms go, even wide open.
No sharpening, 100% crop but a shallow DOF at F/5.6:
With these lenses, really good technique is critical for the best results.
Regards,
Marc