Favorite cameras for adapted lenses

Started 3 months ago | Discussions thread
ThomasB Contributing Member • Posts: 690
Re: BSI sensor

Belgarchi wrote:

ProfHankD wrote:

ThomasB wrote:

Belgarchi wrote:

I would like to know why BSI sensors are better with old lenses.

Here is the explanation:

BSI increases the active area as well as avoiding burying the detector in a deep hole, but that mostly just means it depends less on microlens qualities. The microlenses are still an issue, as is cover glass thickness.

The microlenses are cr*ppy, single-element, lenses, and they don't really focus all the colors to the same spot. You can tune the microlens placements (i.e., not have them regularly spaced) to compensate for rays coming in at unfortunate angles, but that only helps when the rays are as expected.

Thick cover glass actually does at least as much harm if it isn't modeled in the lens design... especially involving CA. Old lenses don't expect 4mm of glass in front of an MFT sensor.

And yet, good photos using old lenses are taken every day..... Amazing.

Did someone compared in practice photos taken with the same lens, with the same parameters, with sensors of similar size and MP, one being BSI and the other not? (and if possible with the same cover glass)

I wonder how much difference it makes.

No, I don't have a 24MP A7 or A7 II for direct comparison. But my A7R II with the BSI-CMOS sensor definitely performs better with these very problematic wide angle RF lenses where the back lens to sensor distance is very short. The old sensor design produces the so called "color shift" with these lenses and the new sensor design doesn't.
It goes without saying that the special developed lenses perform best on these cameras. However, the A7R II does very well with old adapted lenses and even with wide angle RF lenses if stopped down to a certain extent to avoid blurry outer corners when shooting landscapes. But that is more a matter of field curvature from lens design than from any sensor stack issue.
As already stated before: If you want to have a digital mirrorless camera which is able to perform perfectly well even with very old RF wide angle lenses which have been developed for film usage then you have only 1 choice: Ricoh GXR-M.
No camera performs better with these lenses, but it's APS-C only.

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Regards, Thomas Bernardy

 ThomasB's gear list:ThomasB's gear list
Pentax K20D Sony Alpha DSLR-A850 Ricoh GXR Mount A12 Sony a7R II +1 more
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