[baro-nite]

Oh, right, I forgot about the different max shutter speed depending on whether or not you use the leaf shutter.

[ScooterMaxi Jim]

It's not just for jpeg shooting. With the Q the best apertures are at the wide end, because the effects of diffraction kick in around f/5.6 on those tiny pixels. So the time to use it is when you would otherwise have to stop down past f/4 or so even when using the fastest shutter speed. I must admit I haven't done this yet.

I've done some studio testing of the 02 zoom at its longest (weakest) 15mm setting, and f/5.6 is markedly sharper than f/4.5. That isn't to say diffraction isn't a factor already - it clearly is with faster, high quality lenses. Although not posted yet, the Tokina MF ATX 24-40 f/2.8 is sharpest at f/4. This isn't saying that the Tokina is a sharper lens than the kit zoom - it isn't. Every lens will have MTF based on varying factors. But the slow ones tend to do best at f/5.6 because CA and blooming can show up heavily wide open. I will know more when I shoot better, fast primes - 35mm f/2, 50mm f/1.4, 85mm f/1.4 in the studio.

As for the ND issue, you can always carry along your circular PL and add ND to get to those slower shutter speeds. If you don't know the MTF of your lens on the Q, f/5.6 is pretty safe - the limiting diffraction is relatively minor compared to what we tend to assume about the small sensor.

[baro-nite]

I've done some studio testing of the 02 zoom at its longest (weakest) 15mm setting, and f/5.6 is markedly sharper than f/4.5.

Interesting -- photozone found f/4.5 sharper than f/5.6 even at 15mm. I'm wondering if it is a case of contrast vs. sharpness.

[ScooterMaxi Jim]

Interesting -- photozone found f/4.5 sharper than f/5.6 even at 15mm. I'm wondering if it is a case of contrast vs. sharpness.

I don't blame you for questioning. You be the judge. I actually shot the sequence twice because the first time around the varying lenses tested caused color balance shifts in AWB (I should have anticipated that), so then I went with the 5,000 degree WB setting. I don't think there is much question here, at least based on my sample of the lens. I greatly respect Photozone testing, but on this sample I think it is clear I got it right. Not only sharper, but CA around the rabbit ears is much better stopped down (and I do tend to favor images that might be just a tad softer if CA is objectionable). In RAW, I find it much more difficult to clean up CA from adapted lenses on the Q sensor compared to conventional images in LR (not surprising).

Remember that I'm shooting at just over 2 feet. I plan to shoot this unaltered studio test all the way up to 200mm, so these closest shots have to be closer than I would like (my basement can only accommodate a finite distance!). That said, I suspect the results would be pretty similar at 15 feet.

1) 5-15 f/4.5 (AWB)
2) 5-15 f/5.6 (AWB)
3) 5-15 f/4.5 (5000 WB)
4) 5-15 f/5.6 (5000 WB) - this version is posted elsewhere here for comparison (re-posting not allowed) - https://www.pentaxforums.com/forums/pentax-q/209474-adapted-lenses-tested-q-r...ml#post2299949.

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Last edited by ScooterMaxi Jim; 01-29-2017 at 01:05 PM.

[baro-nite]

You be the judge.

A little hard to compare at this scale. The rabbit is certainly softer and maybe with some LoCA in the f/4.5 shots. From 2 feet that could be the difference in DOF. Contrast is better at f/5.6. I'm not at all surprised that the overall subjective perception is that the lens is better at f/5.6, I just don't know if that is because of sharpness per se or because of contrast, aberrations, and/or DOF. Thanks for posting the comparison.

[ScooterMaxi Jim]

Well, the reduced resolution in posting here does make it more difficult. The resolution difference between f/4.5 and f/5.6 isn't particularly close, actually. If you look at the texture on the body of the yellow bird or the fuzz on its head, that's where you can see a real difference.

DoF does make a difference, so the white rabbit doll isn't a good measure for resolution - but it will tell you a lot about CA and blooming problems. I have depth for the scene intentionally because LoCa tends to be pronounced with adapted Q lenses - especially the faster ones.

[glinda]

i get sharp images when i keep the setting on f2.2, 01 lens; and sometimes at 4 or more it is not sharp, wonder if there are variations in the lens and cameras ? love the 01 lens best--- but still, i have not really figured out how to best use the ND filiter, seems very inconsistent results. or like no difference whether on or off.