If Nikon doesn't get their act together on DX...

Started Feb 7, 2013 | Discussions thread
jfriend00 Forum Pro • Posts: 11,355
Re: Who are "we"...

altair8800 wrote:

If you want the same noise on DX as FX at the same shutter speed, you need a wider aperture on DX.

You have to take pixel density into account. In the situation where the FF has fatter pixels, this is true. If the FF has 28Mp for same pixel density as D300 and same level of efficiency, then same noise with same lens.

OK, we're mostly in agreement, but this part of your supposition isn't right.  Noise in an overall image is related to total photons collected not to pixel density.  And an FX sensor collects way more photons than a DX sensor (because it's larger) and thus delivers lower noise.

For example, a D800 has about the same pixel density as a D7000, but much lower noise at the same exposure when the whole sensor is used in both cases.

You may be talking about per-pixel noise (where fatter pixels would appear to be better), but per-pixel noise is not an important characteristic in the visual perception of noise in a viewed image.  If that was the case, then the D800 would have much worse noise than the D4 (because it has much smaller pixels than the D4 and worse per-pixel noise than the D4) but, the D800 does not produce images with worse visual noise in them.  Further, fatter pixels make more visible noise.  In fact, the impact of the D800 per pixel noise is reduced because it has such tiny pixels so the noise artifacts are smaller and more random and thus less visible in a printed or screen viewing of an image.

Nikon has proven with the D800 that they can make smaller and smaller pixels while still making overall images with less visible noise.  Fat pixels aren't necessarily better than tiny pixels.  It's the overall sensor size that really makes the bigger difference.  Collect twice as much light (with a larger sensor) for the same image and you get half as much noise.  It's really that simple.

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