Re: A thinner sensor stack may be possible after all!
I would think the a7 series mod brings performance pretty close to that of the M digital cameras. With that in mind and FWIW, my experience using the M9 and M240 is that the 50 Lux ASPH does have some mid zone dip that can sometimes be seen in images, if you really look for it. It is fine at f/8 and slightly visible at f/5.6. It\'s probable most visible at f/2.8 and f/4. While I haven\'t tested it extensively, it seems to be more problematic at non-infinity distances and may get worse as the subject distance decreases, going by a few years of experience with the lens on digital M bodies. I would expect it to behave very similarly on a modified a7/R/S. While the following isn\'t exactly what you\'re looking for, I did a near infinity cityscape side by side of the a7S and M240, with the M240 files reduced to a7S dimensions. It includes both the 28 Cron and 50 Lux ASPH. If you evaluate the M240 files, I think you should see very close to what you\'ll get with the modded a7S. I also did a similar side by side with the a7R and M9, if you want to see the two lenses at the M9\'s 18MP instead. The links:a7S vs. M240 test and a7R vs. M9 test
The Sony cameras were obviously unmodified, but just want to point that out so no one assumes otherwise. The scene also wasn\'t tilted for corner to corner horizon coverage. Rather, my interest was to see left and right side edge performance. Focus was by live view on the church spire in front of the brown high-rise just left of center.
Coma is a good question... I haven\'t tested for that.
The 28 Cron does have some sharpness falloff towards the edges, though wide open it can look OK for infinity scenes. IMO a fair amount better than the 28 vIII posted by Charlie, but stopping down to at least f/4 helps a lot.
There was also some debate about how critical it was to match correct infinity focus with the actual infinity hard stop on the lens when adapting to the FE mount because many adapters allow focus past infinity. This could potentially be a factor with lenses like the 50 Lux ASPH that rely on a floating element system, that then would be out of tune with the actual subject distance, potentially degrading performance. I think some adapters allow adjustment for this. Reading a recent blog post by Jim Kasson, he seemed to have some luck with Kipon adapters hitting perfect infinity focus.
Charlie: the infinity f/8 scene looks a bit softer along the left side than the right side. Maybe there is a slight decentering of the lens, or a minor adapter problem?
Re: A thinner sensor stack may be possible after all!
I would think the a7 series mod brings performance pretty close to that of the M digital cameras. With that in mind and FWIW, my experience using the M9 and M240 is that the 50 Lux ASPH does have some mid zone dip that can sometimes be seen in images, if you really look for it. It is fine at f/8 and slightly visible at f/5.6. It\'s probable most visible at f/2.8 and f/4. While I haven\'t tested it extensively, it seems to be more problematic at non-infinity distances and may get worse as the subject distance decreases, going by a few years of experience with the lens on digital M bodies. I would expect it to behave very similarly on a modified a7/R/S. While the following isn\'t exactly what you\'re looking for, I did a near infinity cityscape side by side of the a7S and M240, with the M240 files reduced to a7S dimensions. It includes both the 28 Cron and 50 Lux ASPH. If you evaluate the M240 files, I think you should see very close to what you\'ll get with the modded a7S. I also did a similar side by side with the a7R and M9, if you want to see the two lenses at the M9\'s 18MP instead. The links:a7S vs. M240 test and a7R vs. M9 test
The Sony cameras were obviously unmodified, but just want to point that out so no one assumes otherwise. The scene also wasn\'t tilted for corner to corner horizon coverage. Rather, my interest was to see left and right side edge performance. Focus was by live view on the church spire in front of the brown high-rise just left of center.
Coma is a good question... I haven\'t tested for that.
The 28 Cron does have some sharpness falloff towards the edges, though wide open it can look OK for infinity scenes. IMO a fair amount better than the 28 vIII posted by Charlie, but stopping down to at least f/4 helps a lot.
Charlie: the infinity f/8 scene looks a bit softer along the left side than the right side. Maybe there is a slight decentering of the lens, or a minor adapter problem?
Mar 04, 2015 at 11:08 PM
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