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Mamiya CS & E lenses on digital full frame?
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PostPosted: Mon Jul 01, 2019 8:01 pm    Post subject: Reply with quote

Ernst Dinkla wrote:

I compared the Mamiya Sekor CS 135mm 2.8 with the Canon FD 135mm 2.5 and the Minolta MD III 135mm 3.5.
All three on an A7RII, all converted to EF mounts and used on a MC-11 adapter. The last two I like but the M-S shows more CA and the worst defect, which makes it unusable for me, is the purple fringing. Editing that out in capture one with different tools does not make the image better. I was thinking of decentered elements too but given your test I think the CS 135mm is just not up to the competition. Pity as it is about the lightest 135mm 2.8 available.

Best regards, Ernst


I can check these three lenses specifically, if you want. The CS and E 2.8/135mm lenses certainly have more CAs than the others, but i found removing lateral and longitudinal CAs (=purple fringing) quite easy, using Photoshop ...

Stephan


PostPosted: Tue Jul 02, 2019 2:31 pm    Post subject: Reply with quote

stevemark wrote:
Ernst Dinkla wrote:

I compared the Mamiya Sekor CS 135mm 2.8 with the Canon FD 135mm 2.5 and the Minolta MD III 135mm 3.5.
All three on an A7RII, all converted to EF mounts and used on a MC-11 adapter. The last two I like but the M-S shows more CA and the worst defect, which makes it unusable for me, is the purple fringing. Editing that out in capture one with different tools does not make the image better. I was thinking of decentered elements too but given your test I think the CS 135mm is just not up to the competition. Pity as it is about the lightest 135mm 2.8 available.

Best regards, Ernst


I can check these three lenses specifically, if you want. The CS and E 2.8/135mm lenses certainly have more CAs than the others, but i found removing lateral and longitudinal CAs (=purple fringing) quite easy, using Photoshop ...

Stephan


Retouching lateral CAs is working well in Capture One, usually the RGB separations are scaled to one another to get rid of that. Purple fringing can have more causes than just longitudinal CA, flare can have a bad influence and shorter wavelengths into UV as well. The way Capture One suppresses it is by substituting the purple with the two contrasting colors that created it. Quite nifty I think. I think Capture One is a bit too selective on what purple represents purple fringing and by that is less effective on the M-S lens images. If it is not enough I select the purple and desaturate that purple in color correction, that is the common way to make it less visible. One way or another it is easier with the other 135mm lenses than with the M-S one. I have tried an UV filter on the lens, not a very strong one and it did not change anything. Flare could be what makes it worse. In the Minolta MD III 135mm 3.5 I see quite defined purple lines at the contrast edges where the M-S lens has purple flames going into the darker parts. I have made the element edges black with a felt pen (there was nothing on them) but little has changed.

Ernst Dinkla


PostPosted: Tue Jul 02, 2019 8:23 pm    Post subject: Reply with quote

I have added two 100% crops from the same image, taken with the Mamiya Sekor E 2.8/135mm@ f2.8 (wide open).
They show the extreme corner of the 24 MP A7II image.

Image A is the crop from the A7II JPG, showing both lateral and longitudinal CAs (the latter often called "purple fringing").




Image B shows the same crop, but converted with Photoshop, using the "Remove Chromatic Aberration" button AND using the "Defringe" function ("Purple Amount" set to "5", and "Purple Hue" set to "30/70".



Image C - for reference - shows the results using the Minolta / Sony 2.8/70-200mm APO G SSM @ 135mm f5.6. This is a photosoph conversion of the RAW data s well, but no CA correction and no defringing was applied. It show the excellent apochromatic correction if the lens:


Stephan


PostPosted: Wed Jul 03, 2019 1:41 pm    Post subject: Reply with quote

Well maybe Capture One sets a limit on what can be compensated of purple fringing directly and maybe that is not a bad idea either. If I use color correction to reduce the remaining purple then the tree branches become grey in the worst parts and the structure is lost. It is not to boast but prints up to a meter wide show this and that is not what I want. I will start my Photoshop CC to check whether it does a better job to solve this issue but I like to stay within CO. I have no complaints at all about the other M-S vintage lenses, the CS 35mm 2.8 and the SX 55mm 1.8 are used frequently these days. Could be I have a Monday production lens and the other ones are better. Sometimes you win sometimes you lose ...

Thank you for the effort to show all this