RF wide angle lens performance on Sony A7-series

[tb_a]

I recently had a fierce discussion in another forum where I stated that I'm assuming that the new type BSI-CMOS Sensor performs better with some RF wide angle lenses (which are already well known for their restrictions) also in term of corner smearing. I've already seen really bad examples from A7-models with the old style CMOS sensors and compared it with the results from my RF lenses on my A7R II camera with the newer 42MP BSI-CMOS sensor and found them to be not that bad from my camera.

Some folks stated that all A7 models (irrespective of sensor model) perform all exactly equally bad with such lenses. Their theory behind is that the sensor stack is the only influencing factor and all models must have the same sensor stack as otherwise the E-mount lenses wouldn't perform equally good across the whole E-mount platform.

I've found a "sensor stack database" from Roger Cicala on Lensrentals. Obviously the sensor stack theory is wrong as there are E-mount cameras with sensor stacks from 0.6 to 2 mm listed.

Unfortunately nobody was able to present a direct comparison done with the same lens on different sensor models hence this issue is still open.

As I don't own a "regular" A7 I can't do that myself but I would really be curios to see such a comparison.

Not even after extensive search I've found anything on internet. Is anybody able to help?

Any feedback is welcome.

[aidaho]

Upgrading to A7R (1st gen FF BSI-CMOS) eliminated most of the veiling flare from variety of my manual lenses, and significantly changed ghosting patterns.
Just as you are, I can't conclusively say, if this is due to shiny wiring being now hidden behind the photo cells, or just the different filter stack.

One has to have both A7 and A7R to make a definitive claim.

[Nordentro]

I have done some simple tests long time ago. I have my hands on A7 II and A7R III, and I also use to have the A7R (first gen). Colour cast is as good as history on most lenses with the newest sensors and corner smearing and vignetting is much better indeed. Colour accuracy and sharpness is also much better

These samples are from the classic 20mm Russar which is the most challenging symmetrical wide angle RF lens I've had.

A7 II


A7R III


A7R III with some simple PP


An almost useless lens bacame usefull!

[tb_a]

[Nordentro]

Well, I doubt the J-12 is sharp wide open in the corners on any FF format wide open at infinity Should still be possible to draw some conclusion because smearing tends to look slightly different than just unsharp corners.

I have the J-12 and can do a comparison between A7II and A7R III next week 😀 I also have classic lenses like the Nikkor 2.5cm, Canon 25mm and Angulon 21mm in Leica thread and many 28-35mm RF lenses too.

I believe that corner smearing can be reduced with both better sensors and thin filter stack...

[tb_a]

[Nordentro]

Well, I did a comparison recently AND it seems like the corner smearing is almost identical on both A7R III and A7 II. The R is sharper in center and has less vignetting and almost no colour cast in the corners on any lens, but the smearing is still quite obvious. I wonder if some of the smear comes from field curvature, but there is no doubht about that filter thinkness is the biggest reason for bad corner performance on these wide angle lenses.

The Sony sensors have avarage filter thickness compared to other cameras, it's just that Leica have very thin filters and do a better job in this sense. I'm starting to dream about a kolari mod sensor again

[lumens pixel]

Same here for my A7II. But I have red that life becomes difficult in respect of sensor cleaning. Any imperfection on the sensor being much more apparent at shorter distance because of the thinner stack.