FF vs. APS-C - Aperature Behaviour

[Kamelot]

I see and of course understand your point conropl. And you are correct. But if we have 1 biger pixel and 4 smaller pixel, you can not say, that this one bigger will produce stronger signal with less noise. Because maybe that 4 smaller pixels together would produce 2 time stronger signal comparing with that 1 bigger pixel (if the smaller pixel number would be enough bigger).


The main misunderstanding comes from that we are trying to meausre noise level, but do not compare things equaly.


Because there is 3 varying things:

1. pixel size
2. sensor size
3. technology

If we would compare only one thing, leaving two others as constant, there will be less misunderstanding []

[HDNitehawk]

Because there is 3 varying things:

1. pixel size
2. sensor size
3. technology

When the Canon White Paper was written, the 1Ds II was canon's flagship with 16.7 megapixels. Now we have the 5D II at 21 megapixel meaning smaller denser pixels.


#3 matters more than 1 and 2. We know that 5D II will handle noise better.


#1 and #2 are only valid arguments if, you are applying the same technology to both.

[Jon Ruyle]

#3 matters more than 1 and 2. We know that 5D II will handle noise better.

I agree that #1 is irrelevant to the discussion. Talk of pixel density only adds to the confusion.


Tecnhology, however, can only take you so far. Sensors are less than 100% sensitive (ie, they register fewer than 100% of all photons), but the day isn't far off when sensors will be close enough to 100% sensitive that the only real parameter of the three will be sensor size. In the end, it is really effective f number that determines how fast one can expose (or, with a given f number, sensor size is what matters).

[conropl]

But if we have 1 biger pixel and 4 smaller pixel, you can not say, that this one bigger will produce stronger signal with less noise. Because maybe that 4 smaller pixels together would produce 2 time stronger signal comparing with that 1 bigger pixel (if the smaller pixel number would be enough bigger).
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Given the same technology, each area is receiving the same light. So four pixels would have more edges which do not gather light the same, and there has to be some finite space between pixels that do not gather information. This all causes the need to make processing assumptions about what is happening at the edges. Therefore, given the same light energy, the larger pixel gathers more information with less processor interpolation required. And I also contend that when youconvert light energy into some signal, there are losses every time you have to do that. With 4 pixels compared one large one, it would seem you have four times the likelihood of having conversion and processing errors/losses.


I agree with HDNitehawk... technology change is the big equalizer. Comparing the 5DII and the 7D. The pixel density on the 5DII is less than the 7D. The 5DII may have more pixels, but they are spread out over an area 1.6 times bigger. So if you cut down the 5DII sensor to the same size as the 7D, you would only have 13.1 mega pixels compared to the 7D's 18 mega pixels. The 5DII has bigger pixels but less of them over the same area. The end result is a sensor that handles noise better IMO.