more pixels are better!

Started Dec 14, 2008 | Discussions thread
Graystar Veteran Member • Posts: 8,373
Re: SNR vs exposure

Les Olson wrote:

Here is a link to the relationship between SNR and exposure:

http://www.microscopyu.com/tutorials/java/digitalimaging/signaltonoise/index.html

Yeah, seen that. Those Nikon MicroscopyU articles are pretty good.

The key point the graphs make is that you need a lot of light to make
sensors photon-noise limited, ie, to make it true that SNR is related
to total sensor area, rather thaan to the size of individual
photosites.

Well, it's John Sheehy's unofficial job to respond to such suppositions, and I'm not one to step on someone else's territory, except to say that there have been several threads in the past with images demonstrating that, when comparing equal image framing in terms of area (e.g. the entire frame of a 1/2.5” sensor vs. a 1/35th crop of a full-frame sensor) when the 1 2.5” sensor is resized to match the lower resolution of the full-frame crop, the noise levels between the two images appears to be the same.

Personally, I suspect that dynamic range depends on pixel size instead of sensor size (i.e. the resized example above still won't exhibit the same DR as the crop.) But there appears to be evidence that seems to support both views. So my own personal jury is still out on that one. But for noise, I'm in agreement with the those in the high-MP camp who say it's sensor size that matters.

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thw
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