ecarlino wrote: jhinkey wrote: ecarlino wrote: jhinkey wrote:
Well, I don\'t know a lot about the theoretical part of the sensor stack designs, but I do know that my D800 and A7R give (as far as I can tell) the same optical results using the same lenses. Other than the A7R being slightly sharper, lenses that have smearing off in the corners on my D800 have exactly the same behavior on the A7R AND lenses that are sharp into the corners on my D800 are very much the same on the A7R.
Also, I\'ve found that the sensor reflections are identical (as near as I can reproduce) between the two cameras. Now the A7 is a different story as the sensor reflections are much worse compared to the A7r/D800 - one of the primary reasons I bought the A7r over the A7.
So whatever toppings the A7r has over the sensor it seems to act very much identical to the D800.
Also it seems that the exit pupil distance number alone does not correlate to how the lens does off in the corners. My 16/3.5 AI fisheye is excellent across the frame (even wide open) on the D800 and A7r and it has an exit pupil distance of 51.5mm (it\'s pretty much the sharpest lens I own). My 45/2.8P has a slightly larger exit pupil distance (52mm) and it\'s smeary in the borders/corners unless stopped down quite a bit (and even then it never quite goes away at the very far corners). My 20/2.8D (54mm exit pupil) is also pretty smeary off in the borders/corners
So it seems like it\'s a combination of focal length, exit pupil distance, and other lens design attributes that indicate if a lens will do well on a full-frame sensor.
I will sit back and listen again to those much smarter to me on this topic . . . . Great conversation so far.
- John
i\'m no expert either (very far from it), but when you\'re using lenses from other mounts adapted to the e-mount on the A7, the adapter is increasing the flange distance and decreasing the ray-angle into the corners.
the concerns with the ratio between flange distance to sensor stack, or simply the ray angle into the corners, relate to lenses and their native mount measurements.
All I\'m simply saying is that the D800 and A7r sensors when used with identical F-mount lenses show the same results - so at least for these lenses the toppings, if different, don\'t show any differences.
given that Sony makes Nikon\'s sensors, the D800 probably has a similar (I\'m not suggesting identical) stack, so once you\'ve adapted a Nikkor onto the A7r - it should have nearly identical performance because the flange distance will be the same and the stack is similar.
But the sensors and the cover glass/stack are two different things that are separable. So the underlying sensor might be the same, but that doesn\'t mean the glass on top is (AFAIK). Someone else smarter than me will chime in on this.
All I know is that the sensor + glass covering appear to behave very much identical for the F-mount lenses that I have on the D800/A7R.
Aug 29, 2014 at 12:10 PM
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