D600 High ISO in DX

Started Nov 23, 2012 | Questions thread
John Motts
Veteran MemberPosts: 4,997
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Re: pixel pitch and SNR
In reply to Leo360, Nov 23, 2012

Leo360 wrote:

bobn2 wrote:

Photosite (or even pixel) size has very little connection to sensor efficiency and therefore low light performance. The pixels might be bigger, but you have fewer of them, so in the end the same amount of light gets collected.

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Bob

There are two different things here. There is photon count per pixel and number of photons collected per unit area. The latter does not depend on the pixel pitch but the former does. And SNR per pixel gets larger with more photons collected by that pixel (photon shot-noise per photon gets weaker). For the same exposure larger pixels capture more photos and, thus, have higher SNR. This is why pixel peeping reveals more noise-per-pixel for smaller photosites. The price to pay is reduced resolution. With proper down-sampling (bicubic, etc) to the same level of detail one can hope to recover the SNR back by effectively combining outputs of multiple smaller pixels into an aggregate one but doing so does not entirely compensate for read-noise increase.

Correct me if I am wrong, but I think that you will have to jump through several hoops to match 4x4 um pixel SNR to 6x6 um one.

Leo

Doesn't anyone use their eyes anymore? 

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