In response to yesterday’s Nikon/Sony 70-200 testing, a reader commented:
Isn’t it established that Sony lenses are optimized for the Sony sensor and vice versa. (although more skewed against WA due to Sony’s sensor lenses and thickness. Putting the Nikon on the Sony is a little like putting P-Zero’s on a Prius.
I don’t believe that contention is established. In fact, if we’re talking Nikon F/Sony FE, I don’t think it’s true at all.
It is true that lenses are designed for a specific sensor stack thickness (thickness in this case refers to the combination of physical thickness and sensor stack index of refraction). Mismatches between the sensor stack thickness the lens was designed for and the sensor stack thickness of the camera in use can cause corner smear. However, this is only noticeable in cases where off-axis ray angles are such that the corners of the sensor is receiving light at angles that differ in material fashion from perpendicular.
From a practical point of view, this means that you need not worry about corner smear with lenses designed for SLR’s. The designers of those lenses, even if they were designing for the zero stack thickness of film, had to make the lens so that it would clear the flapping mirror, and that in almost all cases has the consequence of moving the exit pupil of the lens far enough from the imaging plane that even corner rays are sufficiently close to perpendicular.
That’s why no one complains about corner smear when film-era Nikon lenses are used on Nikon DSLRs.
It’s also why you can use high quality Nikon F-mount modern lenses like the Zeiss Otus 55/1.4 and 85/1.4, the Zeiss Distagon 15/2.8 DF.2, and the Zeiss 135/2 Apo-Sonnar ZF.2 on Nikon and Sony alpha cameras and get great results on both. The same is true off Leica R-mount lenses.
The other issue with non-perpendicular rays is corner color casting. There are two relevant practicalities here. The first is that the same mirror-avoidant lens designs that make sensor stack a non-issue for SLR lenses also keep material corner color casts at bay. The second thing to keep in mind is that the a7RII back-side illuminated (BSI) sensor and color filter array (CFA) design make it immune to corner color casting even with rangefinder lenses.
The final salient issue is that the Nikon DSLR and the Sony alpha sensor stack thicknesses don’t appear to be that far apart.
For all the above reasons, Nikon F lenses do very well on Sony alpha 7 cameras.
However, there is one thing to consider when doing lens testing: the raw developer. Lightroom looks at the lens data and applies sharpening based on that, which can tilt the playing field in confounding ways. The solution is to use a dumber raw developer such as DCRAW. I didn’t do that yesterday, and that was less-than-perfect experiment design. Eyeballing the images, I don’t see any tell-tale signs of differential sharpening, but I would be remiss if I didn’t point this possibility for error out.
Max Berlin says
I appreciate your constant and relentless pursuit of photography IQ. I see a difference in real life and Imatest results. Life is getting too busy for me to pursue this much anymore but when I get some time I’d like to do an apples to apples Imatest for your Nikon lens. I suspect it’s not up to par if you’re getting equal results from it and the OSS.
In my quick tests I found the Nikon F4 70-200 on the D810 to be sharper than the Sony FE F4 70-200 on the A7R II. The newer lens designs of the F4 zooms seem to be better than the 2.8.
Max Berlin says
Maybe Jim has a bad lens ?
There are lots of possible reasons why Max and I are getting different results:
I have a bad Nikkor.
He had a bad Sony
We tested at different distances
We used different raw developers
We used different targets
We focused differently
We used different numbers of sample images
We analyzed the results differently
I think it is likely that all of the above may be true, if you broaden the first two to include minor sample-to-sample variation in both lenses.
I think all of the above may be operating here. The question is, which are material?
I’m still working on lens testing. The fact that I haven’t posted anything recently means that it’s a hard problem — at least for me — not that I have lost interest.
Hi Jim, I remember reading one of your articles where you compared the edge sharpness of the Otus 55 on the D810 and the A7r http://blog.kasson.com/?p=10382
In the sample pictures you wrote that the A7r Otus images were softer than the D810. Can you explain why?
Do you mean this? http://blog.kasson.com/?p=10382
I’m now putting that down to a7R shutter shock, hard as it is to believe at those high shutter speeds. I’ve not seen anything similar with the a7RII and its EFCS.
Or perhaps you mean this: http://blog.kasson.com/?p=10472
This test has proven difficult to replicate, and in any event the differences are very small.
If you mean this http://blog.kasson.com/?p=10484
It’s definitely a7R (and D810 2nd curtain) shutter shock.
And note this: http://blog.kasson.com/?p=10494
I see. Thank you Jim. Always a pleasure to read your blog. Cheers.
Here are three pics comparing the 70-200 Nikon and Sony F4 @ 200mm and F4.
Thanks for this. It looks like the Nikon lens is the stronger performer in the UR corner. I didn’t look at the D810 file because of the difference in resolution. Are the results any different if you focus on one corner?