[shuttertalk]

Traditionally, lower ISO sensitivity = less grain but less light, and vice versa.

I'm limited to ISO200 by my camera, but what ISO speed do you generally use and why?

[adam]

I used ISO100 whenever possible; just to avoid grain (it's also a smaller file size, so I can take more pictures!!!)
Whenever possible = sunny day outdoors, long exposures at night when I'm using my tripod

Other times when I'm indoors, depending on the lighting, I'll be using ISO200.
and almost at all times, I don't use a tripod indoors.

I'll try to take a picture, and if I've got the aperture wide open, and can't get a fast enough shutter speed, I'll raise the ISO and try again.

[shuttertalk]

ISO100 = smaller file size??

[EnglishBob]

For 95% of shots 100.... once or twice in poor light and trying to stop fast action I'll go higher, but no higher than 400.

[gd]

I'm also limited to 200. I don't see too much noise (barely any) at this setting so it's acceptable to me.

I'm not sure about the smaller size... it's all a ccd to me!

[Cailean]

I have noticed that less colour variation=smaller files size... not sure about the lower ISO... maybe the extra colour in the noise adds to the file size.. just to add insult to injury!!

Anyway, I generally shoot 50 or 100 if there's enough light then I jump to 400... I almost never shoot 200 for some reason. I notice a much bigger difference in quality from 100-200 than from 200-400 so I usually just maximize the light and jump to 400 to keep the shutter-speed up.

[Toad]

ISO 50 - I generally shoot Velvia slide film. On my digitals - I typically shoot ISO 64.

[Petographer]

I normally have it set to 100. When I used my A40 it was at 50 iso most times. I have had times where 1600 was necessary. I find the noise levels pretty low at high iso settings on my D-Rebel.

[StudioJ]

You name it! Although I very rarely shoot at 1600, I do a lot of low light at 800 and if the image is quite bright the noise level isn't as strong. I spend most of my time at 400 unless its bright or in the studio.

The only problem with higher ISO speeds is that your colour saturation drops off fairly quickly.

[adam]

the smaller files size is just an assumption from the fact that my camera decreases the estimated pictures remaining when I increase the iso, and when I decrease the iso, it increases the number of pictures I can take. That's where I got the idea from... ~

[shuttertalk]

Oooh interesting... perhaps the jpeg compression works better on less noisy images because the tonal gradations are smoother...?

[adam]

So many big words in one post! my head can't comprehend! or maybe because of study study study all day long and it's time to sleep!

I usually shoot in RAW now, so the jpeg compression, I guess will only affect the embedded medium JPEG which is saved with the RAW file.

But what you say sounds true! I think

[StudioJ]

The more detail that is in your shot makes for bigger files too, if you have a subject with very shallow DOF the blurry bits take up a lot less space.

Like that techinimical explanation?