Pixel-size, noise and DR.

Started May 12, 2009 | Discussions thread
ejmartin Veteran Member • Posts: 6,274
Re: Clarkvision.com?

Steen Bay wrote:

ejmartin wrote:


It sounds perfectly reasonable when you say that "The saturation
density.. ..turns out to be largely independent of pixel size", but I
knew that my misunderstanding came from somewhere, and I actually
managed to find the source! Near the top of the link below is an
illustration of 'Photon rain' into buckets. The small bucket has much
lower sides than the big bucket, and will therefore overflow long
before the bigger bucket! But that's wrong?


Yes, Roger's graphic is misleading. In an accurate analogy, the bucket would be just as tall, but with a narrower cross-sectional area. Then a large number of tall narrow buckets would have the same holding capacity as one big bucket of the same height.

The rest of that page is mostly a comparison between large and small sensors rather than large and small pixels . As usual with Roger, you need to read carefully; the data doesn't always support the conclusion being drawn, or people are inclined to misinterpret what he is saying on the basis of internet-myth generated preconceptions.

To pick two currently popular cameras, the Panasonic LX3 (2µ pixels) has a saturation density over twice that of the Nikon D3 (8.5µ pixels). In part that is because the LX3 base ISO is 80, as compared to the D3's base ISO of 200. But it shows that there need not be much correlation between pixel size, and the number of electrons per unit area at saturation of the sensor.

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