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Narrowband

Experiment into camera ISO's for imaging- folows on from What ISO thread


narrowbandpaul

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here is a doc I wrote up with regards to how my canon 300D behaves at different ISOs. I looked at gain, read noise, full well and dynamic range, at each ISO.

Its definately worth a look. Also included is a discussion to the implications for imaging, and the method so you can do it for your own cameras.

thanks for looking, feedback welcome

best wishes

Paul

Camera Properties and ISO.doc

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i have just measured the output data. There is more going on in there than I know of.....

i am just using the standard techniques to measure these values

he may be able to unentangle all the various processing steps that happen off chip.

i stand by the measurements though. Conducted in a completely fair way, and produced numbers that make sense.

i could be wrong, but i strongly think not by a factor of 4-5....

paul

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assuming a 50,000DN saturation that 550,000e- full well. That is very unreasonable
Ah, it is these dratted bits again. His values are assuming a 12bit A-D converter - so a max possible of 4096DN. Looking at your figures you are using DN which go up to 65536 (16bit). Not having the camera, I have no idea what numbers really come out in the files, but I think the 300D is only a 12bit camera. This would explain why your read-noise was the same but the gain apparently different (although just to add confusion, shouldn't it be 16x !?).

NigelM

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