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03-14-2013, 03:24 PM   #1
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90mm on 645 film?

Has anybody shot their new 90mm DFA lens on a 645 film body to see how it holds up in the 60mm image circle? Ristretto indicated that his copy had corner darkness at 2.8 on his 645D. Edge darkness on 44mm image circle is a concern on a lens that is being marketed as covering 60mm image circle. Please let us know if anyone has tested a copy on 645 film camera.

03-15-2013, 12:59 AM   #2
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QuoteOriginally posted by 672 Quote
Has anybody shot their new 90mm DFA lens on a 645 film body to see how it holds up in the 60mm image circle?
Yesterday I received first film from photo laboratory. Wonderfull full-frame (56x41,5mm) lens, no any darkness in the corners.
Neither during shooting (in the viewfinder of 645NII), nor in photos. Neither with the open aperture at infinity, nor with closed aperture of course.
Wait a little - I'll show the samples from film camera. Technical quality of the lens is also excellent.

QuoteOriginally posted by 672 Quote
Ristretto indicated that his copy had corner darkness at 2.8 on his 645D. Edge darkness on 44mm image circle is a concern on a lens that is being marketed as covering 60mm image circle.
1. May be at the very close distance he catch the shade from the lens hood,
it's noticeably bigger than lens hood of the FA 120mm/f4.0 Macro.

2. Or may be it's my mistake and I do not see defects, because of overall admiration about the lens
In any case, wait a little - I'll show the samples from digital camera too.
But my first impression is the same: no darkness in the corners at 44x33mm sensor.
03-15-2013, 07:15 PM   #3
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thank you mannagger! look forward to see scans from lens.
03-15-2013, 10:28 PM   #4
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Same here, really look forward to see the shots

03-16-2013, 09:02 AM   #5
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Same here, really look forward to see the shots...

In the meantime please have a look at the following examples. Brick wall in a distance of about 15 feet (5 meter). Two shots, one with 2.8, the other with 11. From each shot three versions: overview (whole picture), crop center and crop corner down right (I had to split it on two posts...)

I think it's obvious... If it would be the lenshood, then it would appears on all apertures, not only at 2.8.

In fact, for me that vignetting isn't really a problem. When I shoot on 2.8 it's because I like to point out the principle thing in the picture. And this rarely is found on the corners... In addition vignetting is one of the problems that can easily be corrected by any RAW-Converter. As soon as Pentax will deliver a special profile for this lens, Lightroom, Photoshop etc. can do this even automatically.
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03-16-2013, 09:03 AM   #6
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And here the crops...
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PENTAX 645D  Photo 
03-17-2013, 12:58 PM   #7
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Thank you for the great photo test of this corner darkness at 2.8!
03-17-2013, 01:04 PM   #8
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Thank you for the great photo test of this corner darkness at 2.8!

03-18-2013, 02:32 AM   #9
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1. Here you are my samples:
indoor and film
Pentax 645D test DFA 90/2,8 indoor - managger -
outdoor
Pentax 645D test DFA 90/2,8 outdoor - managger -

You can click on "original size" and download every photo.
If you want to download all photos at once (in original size) - here you are two archives:
Indoor.7z
Outdoor.7z

QuoteOriginally posted by 672 Quote
Ristretto indicated that his copy had corner darkness at 2.8 on his 645D.
2. So, I have found his direct words about this subject in the neighbor thread:
https://www.pentaxforums.com/forums/pentax-medium-format-645-6x7-645d/214034-...ml#post2269456
"Real macros I didnít yet test out very deeply. What I noticed is a vignetting on aperture 2.8 for about 0.5 Ė 1 stop in the corners."

He did not speak about "dark corners" - he speak about "vignetting" !
As for me, "dark corners" means that the lens is not a "full-frame" on 56x41,5mm,
and "vignetting" means little worsening in the corners at the open aperture on 44x33mm, nothing more.

3. I can add some information to this question.
Have a look at the standart focus-chart:
DI_04313.jpg - Pentax 645D test DFA 90/2,8 indoor - managger -

Click on original photo: 7264 x 5440 (14,4 Mb)
Pay attention to the corners - the text "3 1/8" is slightly worse than the text "2 3/4".
It's absolutely normal I think, because every lens performs it's best in the center,
and of course starts to decrease resolution sooner or later, especially at open aperture.

QuoteOriginally posted by Ristretto Quote
I think it's obvious... If it would be the lenshood, then it would appears on all apertures, not only at 2.8.
In fact, for me that vignetting isn't really a problem. When I shoot on 2.8 it's because I like to point out the principle thing in the picture. And this rarely is found on the corners... In addition vignetting is one of the problems that can easily be corrected by any RAW-Converter.
Thank you, my observations are the same, and thoughts are the same too
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