|Posted: Mon May 07, 2018 10:08 am Post subject: Re: Mamiya Sekor C 4/210mm apochromatic correction?
|Some months ago I got a tilt/shift adapter for my Mamiya 645 lenses. Some preliminary test gave excellent results for the Mamiya telephoto lenses, but not so for the Mamiya Sekor C 3.5/35mm (for which a shift adapter would make sense). Therefore I forgot a bit about using these Mamiya Sekor C lenses on my A900.
A few days ago i checked a Leica 3.4/180mm APO Telyt on 24MP FF - with stunning results; the lens is even a trace better than the Minolta AF 2.8/200mm APO G.
This gave rise to a small test of a few fast 180mm / 200mm lenses. Out of curiosity I did include the Mamyia Sekor C 4/210mm.
The results of the Mamyia were stunning as well; this lens obviously is very well corrected - certainly better than the AF ED Nikkor 2.8/180mm, and at f8 it has less CAs than the Minolta AF 2.8/200mm APO.
Below are 100% crops from the corners; the JPGs are directly out of the Sony A7 (24MP FF).
Canon new FD 2.8/200mm IF: The optical performance of this lens is the worst of the bunch tested here. As others have mentioned, its CAs are pretty hefty, and focusing is not as precise as with non-IF lenses (the same is true for the AF Nikkor 2.8/180mm; the Minolta AF 2.8/200mm APO, however, has a more precise IF mechanism). We can an assume that the nFD 2.8/200mm has two large lenses out of LD glass (Abbé number 70) - at least the nFD 4/200mm, nFD 4/200 Macro, and the nFD 4/300 (non-L) do have them. Obviously this is not sufficient to give a good color correction.
Konica Hexanon AR 3.5/200mm (latter version): medium performance; less CAs than the Canon nFD 2.8/200mm IF and the Pentax SMC 2.5/200mm, but more CAs than the Mamiya/Minolta; good details, but lowest contrast of the six lenses tested, and not-so-good colors (especially compared to the Minolta AF 2.8/200 APO).
Mamyia Secor C 4/210mm: What a surprise! At f8 the best color correction of all lenses tested here, and absolutely comparable to the legendary Leica APO Telyt 3.4/180mm. The Minolta APO may have slightly betters colors, though (more "punchy"). Details are excellent (also at f4; not shown here).
Minolta AF 2.8/200mm APO: slightly more CAs than the Mamiya, and slightly better colors / contrast I would say. Please note that the crop shown here was taken at f4 (and not at f8 as the others) - I simply had forgotten the f8 shot. Together with the Mamiya Sekor C 4/210mm this is the best lens of the bunch. Easy and quick manual focusing without any play (the Nikkor AF and the Canon nFD are much worse in this respect!).
Nikkor AF 2.8/180mm ED (newest version): medium performance; detail resolution not as good as with the Minolta AF 2.8/200 APO and the Mamiya Sekor C, but better corners than the Canon nFD 2.8/200 and the Pentax SMC 2.5/200. The same is true also concerning the CAs. Manual focusing is a bit annoying since the focusing mechanism has quite a bit of "play" (a problem that plagues also the Sony Zeiss ZA 1.4/85mm and ZA 1.8/135mm).
Pentax SMC 2.5/200mm: Quite a bit of CAs (less than the Canon, though) and a relatively low resolution, even at f8. Slighty better than the Canon, and a bit faster than the others, of course.
And now an important technical remark about testing: The E-mount bayonet of the Sony A7 series is very badly made. Whne attaching a fast / heavy lens, the mount will easily tilt about 0.5mm - which makes lens testing meaningless. I have reduced this problem by not using a tripod; instead i put the camera and lens directly on a stable basis.
Of course now we all are curious about the Mamiya Sekor C 5.6/300mm...
The Sekor N 300/5.6 has less chromatic aberration than bot the the N Sekor 210/4 and Leitz Apo Telyt R 180/3.4 on the Sony A7/7R/72.
I got all the lenses tested/mentioned above,save the Minolta 200/2.8.Sekor N 300/5.6,though not as sharp as The Apo Telyt R 180/3.4,is the best apo corrected lens of them all.