D600 High ISO in DX

Started Nov 23, 2012 | Questions thread
noirdesir
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Re: pixel pitch and SNR
In reply to John Motts, Nov 23, 2012

John Motts wrote:

noirdesir wrote:

John Motts wrote:

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?

When you buy tomatoes, to 'weigh' them with your hands to figure out which box contains more or do you put them on a balance? If something can be done faster and more accurately with the help of technology, it is usually more sensible to use the technology.

Simple statistics tell us that the read noise component for a combination of these four smaller pixels is: rn(com) = square root of (1.5^2 + 1.5^2 + 1.5^2 + 1.5^2) = 3 e-

Fair comment, but everyone knows how to use scales.

However it's a good deal more straightforward to just compare images with your eyes than to go into this technical depth that leaves most people in the dark. Your "simple" statistics quoted above for example.

There are people coming in to photography who read all the techno stuff but still haven't got a clue about the most basic concepts.

Photography is getting unnecessarily complex and it is this that leads to the most unbelievable misunderstandings of quite basic photographic concepts that we so often see on these forums.

Very little of this techno stuff is essential to produce good photography and is more relevant to camera design rather than camera use.

I don't wish to take anything away from your technical knowledge and it's great if you're interested in that area, but it's specialist stuff and it's a shame if we lose sight of photography itself.

But if somebody has a question that is easily answered with simple statistics, why not give him him or her the answer if you know it?

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