Originally posted by snostorm Longer working distance will always give you deeper DOF
At the same aperture, yes. But on the Q you can't stop down very far before diffraction kills detail.
I'm very curious about this so did a quick test. Using the Sigma 70/2.8 macro, I did some 1:1 shots on the K10D, and then some shots with the same lens on the Q, trying to keep the subject the same size
similar, relative to the size of the sensor. Didn't get it exactly but close enough for this test, simply meant as a rough comparison. These are 50% crops from the K10D and ~44% crops from the Q. If you're on a wide monitor, make the window wide and you can view pairs side-by-side.
Wide open and the difference in DOF is indeed dramatic:
Stopping down to f/16, the K10D is still reasonably sharp, whereas the Q is total mush:
Now here's f/5.6 and f/8 on the Q. I think the f/5.6 shot compares well to f/16 on the K10D in both DOF and resolution. f/8 on the Q is significantly softer.
Again, this is a rough comparison. But it is enough to convince me that the DOF advantage on the Q is pretty much completely countered by diffraction. So the Q's main advantage for macro is working distance, and the ability to use ordinary lenses for near-macro without extension or diopters. I repeat, this advantage is not to be sneezed at.
Last edited by baro-nite; 04-05-2013 at 05:40 PM.