Originally posted by falconeye What has been said here about the diffraction limits is not accurate.
I tried to make a more accurate statements here:
Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, 100% crops look visibly soft).
Therefore, shooting a DA*300 or DA*60-250 with a Q at their sharpest aperture (about f/5.0) will still deliver plenty of detail a K-5 won't render.
But the additional reach will not be that of the crop factor. It will be only roughly be 2-2.5 vs. a K-5 (because you can crop a K-5 image more). And only about 1.8x vs. a 24MP K-5mkII or NEX7, i.e., not more than what a 1.7x TC provides. OTOH, the * lenses do resolve enough detail to exploit this ~2x factor near the center.
Hi Falk,
Thanks for doing the math! Your calculations pretty much confirm what I felt intuitively -- that my premium teles would work pretty well with the Q + adapter. The thing that I didn't factor into my considerations was the comparison with K-5 crops, so the actual advantage will not be as great as I had anticipated
.
Luckily, I have some really good teles to play with -- D FA 100/2.8 Macro, Tamron SP 180/2.5, Sigma EX 180/3.5 Macro, A* 200/2.8, FA* 300/4.5, FA* 300/2.8, Sigma EX 300/2.8 APO, so it should still be fun as these all resolve pretty well wider than f5.6. . . now I need to find some tripod rings for some of these lenses. . .and a very good light tripod -- it never ends. . .
The IQ also holds up pretty well with most of these lenses with the Sigma EX 1.4x APO TC or the F 1.7x AFA, so these will also be worth a try with the faster lenses, IMO.
Scott