What is the point of raising the ISO setting on a camera?

Question

doesn't it just lower the image quality and add noise?

Answer 1

Yes, to a point and allot depends upon the make & model in which you are using, I have only tried it a few times to see the difference but went from 400 to 800 ISO with my Canon XTi. I could not see a difference.

I have been told that beyond 800 ISO things start become noticiable because of the noise factor.

Answer 2

Sometimes you need it in order to get the speed to handhold the camera

Answer 3

Yes, it does.  But for low-light situations, sometimes it's not practical to increase aperture or decrease the shutter speed to get more light.  I'd rather have a noisy picture than a blurry picture caused by needing too slow a shutter speed.

Answer 4

Well, yes it does. But if you raise the ISO, it brightens the image, which allows you to use a faster shutter speed (which darkens the image) or set the camera to a  smaller aperture. (also darkens the image)

So say you need to set the camera to f/22. You would use a higher ISO than if you were setting it to f/1.8.

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Answer 5

1. A faster shutter speed stops action.

2. A smaller aperature (higher f/number) increases depth of field.

3. A lower ISO speed increases resolution.

You usually get to pick two of the above and sacrifice the other.