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03-15-2009, 02:42 PM   #1
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Boring 100% center crops of K20D + DA 17-70 SDM f/4

I have neither the time nor the patience to do a thorough test, nor do I have a USAF resolution test chart handy, but here's something for all fellow casual pixel peepers. My observation was that the results are pretty much indistinguishable at f/4 (wide open) and f/5.6. The only difference could be that in one case, the lens is focused spot on and in the other it's not--I refocused before each shot. I also tested for front and back focusing and didn't notice anything...well...noticeable with my inexact noticing.

Both are at 70mm. Now, now, keep in mind, it's a zoom. One of these is f/4. Another is f/5.6. (It may surprise you which is which.) I used a (rather unsteady) tripod, cable switch, mirror lockup, ISO100 etc. The exposures were relatively long (~1/3s).

EDIT: I removed the crops: I'm thinking of redoing this with black on white text...So do ignore.

EDIT2: This testing obsession can easily get out of hand: I think I may end up with an ISO resolution test chart.
For my own good, I think I'm going to take a break. So if anybody has stumbled upon this post by accident, for now, I must direct you to photozone's test which unfortunately is done on a K10D, not a K20D.

EDIT3: If you came here by accident, here's a less boring 100% center crop, K20D, f/4, 70mm.




Last edited by asdf; 05-21-2009 at 09:20 PM.
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accident, chart, crops, da 17-70 sdm, f/4, k-mount, k20d, pentax lens, slr lens, test
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