Finally found an M mount 28mm for A7
Old 02-13-2014   #1
thompsonks
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Finally found an M mount 28mm for A7

I read a bunch of reviews/comments, tried several M-mount 28s Summicron, Skopar, Ultron and finally ended up with one that works, at least for me, on A7: Konica M-Hexanon 28mm f2.8.

I was most disappointed in the Summicron because it wasn't just soft in the corners, it smeared them at an angle from f2-f4. The CV 28 Skopar vignetted too much to be taken seriously. The Ultron was Ver. 1 (f1.9), which doesn't focus shift like the newer version. It was quite a bit better: not the sharpest knife in the drawer, but acceptable with no serious smearing; just some color vignetting in the blue channel. I could've lived with this one, but the Hexanon was about the same in corner sharpness and noticeably better in the center. And it vignetted without as much blue in the corners. It doesn't smear, though it isn't remarkably sharp at the outer edges. I believe that's the lens itself not specific to its use on A7 sensor. So this one turned out to be the best compromise among those I tried.

(I didn't try 28 Elmarit Asph because I found it too contrasty on M8/9 not a good 'sunny day' lens; so I'd traded it for Summicron.)

This was shot at f11, but at larger apertures it also performed best among the four.

[IMG]
Urban clearcut by thompsonkirk, on Flickr[/IMG]
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Old 02-13-2014   #2
uhoh7
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Quote:
Originally Posted by thompsonks View Post
I read a bunch of reviews/comments, tried several M-mount 28s Summicron, Skopar, Ultron and finally ended up with one that works, at least for me, on A7: Konica M-Hexanon 28mm f2.8.

I was most disappointed in the Summicron because it wasn't just soft in the corners, it smeared them at an angle from f2-f4. The CV 28 Skopar vignetted too much to be taken seriously. The Ultron was Ver. 1 (f1.9), which doesn't focus shift like the newer version. It was quite a bit better: not the sharpest knife in the drawer, but acceptable with no serious smearing; just some color vignetting in the blue channel. I could've lived with this one, but the Hexanon was about the same in corner sharpness and noticeably better in the center. And it vignetted without as much blue in the corners. It doesn't smear, though it isn't remarkably sharp at the outer edges. I believe that's the lens itself not specific to its use on A7 sensor. So this one turned out to be the best compromise among those I tried.

(I didn't try 28 Elmarit Asph because I found it too contrasty on M8/9 not a good 'sunny day' lens; so I'd traded it for Summicron.)

This was shot at f11, but at larger apertures it also performed best among the four.

[IMG]
Urban clearcut by thompsonkirk, on Flickr[/IMG]
Nice find

Also at this level are:

M-rokkor 28
Cron 28
Elmarit v2 and v3.

Speaking about A7, not the R.
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Old 02-13-2014   #3
Godfrey
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Quote:
Originally Posted by thompsonks View Post
I read a bunch of reviews/comments, tried several M-mount 28s Summicron, Skopar, Ultron and finally ended up with one that works, at least for me, on A7: Konica M-Hexanon 28mm f2.8.

I was most disappointed in the Summicron because it wasn't just soft in the corners, it smeared them at an angle from f2-f4. The CV 28 Skopar vignetted too much to be taken seriously. The Ultron was Ver. 1 (f1.9), which doesn't focus shift like the newer version. It was quite a bit better: not the sharpest knife in the drawer, but acceptable with no serious smearing; just some color vignetting in the blue channel. I could've lived with this one, but the Hexanon was about the same in corner sharpness and noticeably better in the center. And it vignetted without as much blue in the corners. It doesn't smear, though it isn't remarkably sharp at the outer edges. I believe that's the lens itself not specific to its use on A7 sensor. So this one turned out to be the best compromise among those I tried.

(I didn't try 28 Elmarit Asph because I found it too contrasty on M8/9 not a good 'sunny day' lens; so I'd traded it for Summicron.)

This was shot at f11, but at larger apertures it also performed best among the four.
Interesting, and useful. Thanks.

I have both the Color Skopar 28/3.5 and the Ultron 28/2. I have no real hopes that the CS28 will do well ... that lens design just isn't a very successful match to FF digital sensors and has problems even on the Leica M9. It does well on the Ricoh GXR, but that's APS-C.

I did some very fast preliminary tests with the Ultron 28/2. Corners are soft wide open (even on film), by f/4 it is improving enormously, and by f/5.6-f/8 it seemed fine in my test. But I'll put it on a tripod and do a more rigorous test over the weekend. (I can see it doesn't perform as well as my Elmarit-R 24/2.8 ... either wide open or anywhere else; I can see that already. What it has going for it is compactness.)

I understand from some other reports that the M-Rokkor 28mm does well too.

G
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