ISO with bird pictures

I've been trying to take pictures of birds but seem to get a lot of noise shooting at ISO400. If I can capture a bird sitting quietly on a branch would an ISO of 200 reduce the noise in half if the other settings were the same. I use a S 2IS, maybe the glass in the optical zoom is an issue as well? Any suggestions.

I have the same problem with my S2IS, too. Unfortunately, if you don't use the higher ISO, you won't be able to use the shutter speed you need to prevent motion blur or stop action. I've resorted to using Noise Ninja to get rid a lot of the noise but I just can't get rid of all of the noise without losing image detail.

Re your ISO 400 vs ISO 200 question, you will get less noise at ISO 200 than at ISO 400 but I can't tell you if it'll be half or not.

if your exposure was perfect at iso 400 and it was underexposed at iso 200 (and lightened in PP), the iso 200 picture would show more grain. Use whatever iso that will get u a 1/focal length for shutter speed or faster to prevent camera shake.

timc wrote in post #3716135
I've been trying to take pictures of birds but seem to get a lot of noise shooting at ISO400. If I can capture a bird sitting quietly on a branch would an ISO of 200 reduce the noise in half if the other settings were the same. I use a S 2IS, maybe the glass in the optical zoom is an issue as well? Any suggestions.

Welcome to the world of small-sensor cameras.

Noise is not linear. The noise at ISO 200 is a lot less than half the noise at ISO 400.

The S2IS has relatively good glass. Besides, while bad glass may cause distortion and/or a loss of contrast, it does not affect noise.

Digital camera images have no grain. They came pixellate if over-enlarged, but that's not the same thing. And post-processing does not increase noise.

If you are serious about bird photography, you need a better camera. It might be time for you to take the step to DSLRs. For birding, get the best long lens you can afford, and then budget in a 1.6× body. A used 300D (Digital Rebel) with good glass will produce much better results than a new 30D with cheap glass.