ISO and digitalcamera (C4040)

I do not understand the ISO selection on my camera C4040 ( or any other digital camera), what is it that changes going from ISO 100, 200, to 400?

In advance thank you very much.

Best regards, Henrik

In photography terms it's setting the film speed. Setting to ISO100 is equivalent to puting ISO100 or ASA100 film in the camera ...etc.

In circuit terms it's setting the gain of the output amp of the CCD; bigger number -> more gain, more noise.

Herb

recommended ISO film speed underwater is 100 anything higher can cause noise or grainy results.

It seems that most shots I've seen are at ISO 100 or ISO 50 (G2)...would there be any situations where you'd want to use anything above that?

I used to use ISO 200 films when shooting wrecks ... gained one f-stop on my old MX-10 but this is irrelevant for digital cameras.

Maybe ISO 200 is not too noisy for low light situations when you cannot use a strobe.

Sabine

My point is, if the quality is grainier at higher ISOs, why do manufacturers even bother with them?

Because there are times when you might be willing to trade image quality for a proper exposure, if that's the only way you can get the shot.

Richard

Maybe I'm nuts, but I cannot see the differnece above water between ISO400 & 100...

I just shot some low light pics inside the chapel at the Santa Barbara Mission on my Canon D5 and cannot for the life of me see a difference.... maybe it is my old eyes but am I the only one who can't see the difference??

For underwater you'll want to leave your 4040 on ISO 100. Here's a good article for you: http://www.digitaldiver.net/lib_docs/olyprimer.pdf