more pixels are better!

Started Dec 14, 2008 | Discussions thread
Graystar Veteran Member • Posts: 8,373
Re: more pixels are better!

boels069 wrote:

Is the noise independent of shutter time?
(ISO 6400 @ 1/8000s has the same noise as ISO 3200 @ 1/4000s ?)

As with all these kinds of technical nuances, the true answer is long and complex. However, I'll try to keep it simple.

First, a change in ISO changes everything because you're changing the actual exposure to light. So I'm rewriting your example to match what I had written...f/2.0 @ 1/8000s vs. f/2.8 @ 1/4000s.

Simply stated, even with different shutter speeds, shot noise (noise from the light itself) will be the same as long as exposure is the same. Read noise (noise added by the electrical going-ons in the sensor) will be different. That difference in read noise is practically negligible when comparing two such fast times. It gets worse as the shutter speed gets slower. At 1.3 seconds, Canon compacts are already performing a dark-frame subtraction to get rid of the extra sensor noise. I haven't seen any tests of a sensor's noise across the more typical shutter speeds (1/30s to 1/1000s.) If anyone knows of any, post a link. Should be interesting.

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