Diffraction and our Q

CologneKiwi · 12-04-2012, 02:06 PM

My experience backs up what the TO has found out. Having read about the diffraction figures relevant to the Q (on Photozone, for example), I had assumed that it would be best to use long lenses wide open. But in test shots I found that the M*300 performed better at 5.6 than at 4. I shot the Sigma telemacro 400 at 5.6, 8 and 11 and got the best results at f8. So it seems to be very much a case of finding what works best with any particular lens.

**mike.hiran** · 12-05-2012, 10:49 PM

very interesting test; thanks for posting and doing this!

**crewl1** · 12-05-2012, 10:59 PM

I can confirm (now that I read the manual for the Pentax adapter and found the translation scale) that the DA*300 looks best on the Q around 5.6 (#1 stop), and also the Sigma 70-200 performs nicest at 5.6 (#2 stop).

I use the DFA 100WR primarily for macro on the Q, so to maximize DOF I use it at f8 or f11, but it is sharpest closer to f4.

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12-04-2012, 02:06 PM	#16
CologneKiwi New Member Join Date: Sep 2012 Posts: 2	My experience backs up what the TO has found out. Having read about the diffraction figures relevant to the Q (on Photozone, for example), I had assumed that it would be best to use long lenses wide open. But in test shots I found that the M*300 performed better at 5.6 than at 4. I shot the Sigma telemacro 400 at 5.6, 8 and 11 and got the best results at f8. So it seems to be very much a case of finding what works best with any particular lens.

12-05-2012, 10:49 PM	#17
mike.hiran Site Supporter Join Date: May 2007 Location: portland Photos: Albums Posts: 1,491	very interesting test; thanks for posting and doing this!

12-05-2012, 10:59 PM	#18
crewl1 Site Supporter Join Date: Jul 2010 Location: Los Angeles, CA Photos: Gallery \| Albums Posts: 9,807	I can confirm (now that I read the manual for the Pentax adapter and found the translation scale) that the DA*300 looks best on the Q around 5.6 (#1 stop), and also the Sigma 70-200 performs nicest at 5.6 (#2 stop). I use the DFA 100WR primarily for macro on the Q, so to maximize DOF I use it at f8 or f11, but it is sharpest closer to f4.