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04-18-2021, 11:47 AM   #1366
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QuoteOriginally posted by ZombieArmy Quote
These are products that are expected to be in the lineup for a very long time. And I don't think Pentax is a company that can afford to screwup at launch and get away with it these days.
They never could afford to screw up - but perhaps they didn't realize that at one time.
Some people are still judging in-lens AF motors assuming that they might be as bad as some early 'SDM' ones were.

04-18-2021, 12:09 PM - 1 Like   #1367
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QuoteOriginally posted by Smolk Quote
I keep thinking, when the Nikon Z 14-30mm (which has terrible curvature) can be corrected by a lens profile, can't the 21mm be too?
This may well be my ignorance in these matters.
Field curvature is not something correctable by software as it isn't a distortion. It's the shape of the plane of focus.
04-18-2021, 12:52 PM - 1 Like   #1368
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QuoteOriginally posted by Smolk Quote
I keep thinking, when the Nikon Z 14-30mm (which has terrible curvature) can be corrected by a lens profile, can't the 21mm be too?
This may well be my ignorance in these matters.
The only thing you can really do is just stop down enough that depth of field compensates some. But the DA 15 really needs f8 on APS-C to have focused edges when the center is in focus. I haven't shot the DA 21, but I think it is similar, but not quite as bad.

This is an article that does a pretty good job of explaining the issue: Field Curvature, A Tricky Problem in Photography | PetaPixel As you can see, field curvature makes focusing really tricky and makes it difficult to have it maintained on both center and edges at the same time without stopping down a bunch.
04-18-2021, 02:00 PM   #1369
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D fa 21

Oh be still my beating heart.! Looks a lot larger than the old FA 21 though.

04-18-2021, 10:52 PM   #1370
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QuoteOriginally posted by Wheatfield Quote
Field curvature is not something correctable by software as it isn't a distortion. It's the shape of the plane of focus.
Yep, nothing one can do here but close the aperture.
04-19-2021, 07:58 AM   #1371
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QuoteOriginally posted by Rondec Quote
The only thing you can really do is just stop down enough that depth of field compensates some. But the DA 15 really needs f8 on APS-C to have focused edges when the center is in focus. I haven't shot the DA 21, but I think it is similar, but not quite as bad.

This is an article that does a pretty good job of explaining the issue: Field Curvature, A Tricky Problem in Photography | PetaPixel As you can see, field curvature makes focusing really tricky and makes it difficult to have it maintained on both center and edges at the same time without stopping down a bunch.
Da 15 field curvature is one of its biggest assets. Not all wide angle lenses need to have completely flat focus plane.
04-19-2021, 08:11 AM   #1372
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QuoteOriginally posted by taktoon Quote
Da 15 field curvature is one of its biggest assets. Not all wide angle lenses need to have completely flat focus plane.
Can you elaborate on that? I'm genuinely interested in the reason.
04-19-2021, 08:14 AM   #1373
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This lens needs to hurry up and take my money....

JJ

04-19-2021, 11:49 AM   #1374
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QuoteOriginally posted by hongman Quote
Oh be still my beating heart.! Looks a lot larger than the old FA 21 though.
Pardon me, but there is no FA 21, there is only FA 20 and DA 21(then there is FA 24/2 which is different beast all together), both should be smaller than this coming DFA 21.
04-19-2021, 02:39 PM - 1 Like   #1375
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QuoteOriginally posted by Smolk Quote
Can you elaborate on that? I'm genuinely interested in the reason.
Imagine you have a group of 10 people, get them to stand in a close curve around you. You'll get them all in and if you do it well, no distortion
04-19-2021, 02:56 PM - 1 Like   #1376
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QuoteOriginally posted by Smolk Quote
Can you elaborate on that? I'm genuinely interested in the reason.
Roger Cicala did a very good explanation of field curvature at dpreview. Itís a multipart thing starting in December, with loads of details.

-Eric
04-19-2021, 03:07 PM   #1377
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QuoteOriginally posted by TwoUptons Quote
Roger Cicala did a very good explanation of field curvature at dpreview. Itís a multipart thing starting in December, with loads of details.

-Eric
I believe it's getting worse with mirrorless cameras as well, I know the Fuji 27mm pancake has a huge problem with it.
04-20-2021, 02:00 AM   #1378
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QuoteOriginally posted by jct us101 Quote
I believe it's getting worse with mirrorless cameras as well, I know the Fuji 27mm pancake has a huge problem with it.
Some of the mirrorless lens offerings are more software corrected than optically corrected.
04-20-2021, 02:12 AM - 1 Like   #1379
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As mentioned you can't software correct field curvature. Typically this means they they focus on getting sharpness, field curvature and longitudinal CA sorted with glass whilst leaving vignetting and distortion for software. It's easier to make sharp lenses with distortion and vignetting than perfect all around. Leaving the milcers with an advantage in lens design.
04-20-2021, 07:05 AM   #1380
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QuoteOriginally posted by house Quote
As mentioned you can't software correct field curvature. Typically this means they they focus on getting sharpness, field curvature and longitudinal CA sorted with glass whilst leaving vignetting and distortion for software. It's easier to make sharp lenses with distortion and vignetting than perfect all around. Leaving the milcers with an advantage in lens design.
Thatís not unique to mirrorless. Ricoh could implement that in SLRs and take that approach. They already offer some level of lens correction in-camera. They just havenít taken the Sony approach to aggressive correction...

-Eric
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