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DPChallenge Forums >> Hardware and Software >> a bit technical question ...
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 05/06/2004 09:59:16 PM · #1
Hi,
what is it exactly that i am adjusting when i'm changing the ISO numbers for a digital camera ?
i know Shutter speed controls the length of time the shutter is opened and aperture values are for the opening size.
how about ISO numbers ? is it changing the gain on the CMOS sensor ?

thanks in advance
 05/06/2004 10:04:17 PM · #2
Yes, gain/sensitivity.
 05/06/2004 10:15:02 PM · #3
Basically the speed of the exposure. The higher the ISO number, the quicker the exposure. Also, the higher the ISO, the more noise/grain you will see.
 05/06/2004 10:25:12 PM · #4
Whether or not the sensor is CCD or CMOS, the iso setting changes the gain of the processing amplifier. Higher gain values ie. higher ISO values, will dredge the last few electrons out of the quantum wells, including those produced by thermal activity. That is why higher ISO settings produce noiser images.
The amplifier itself also contributes to the noise because of it's thermal sensitivity. The bottom line: use the lowest practical ISO setting that will still get the shot.
 05/06/2004 10:56:29 PM · #5
Originally posted by ElGordo:
Whether or not the sensor is CCD or CMOS, the iso setting changes the gain of the processing amplifier. Higher gain values ie. higher ISO values, will dredge the last few electrons out of the quantum wells, including those produced by thermal activity. That is why higher ISO settings produce noiser images.
The amplifier itself also contributes to the noise because of it's thermal sensitivity. The bottom line: use the lowest practical ISO setting that will still get the shot.


exactly as i thought
thanks for the detailed answer
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