[DPB1]

Can anyone let me know how they gauge what ISO setting to use for particular circumstances.

I have a Nikon D200 and have got Auto ISO set, but wondered if this set the ISO dependant upon what ISO is manually set at.

For example, if I have manually set the ISO to 200, how does the Auto ISO setting work ?

Is it fair to say that if it is a bright sunny day the ISO setting should be set at ISO 100 ?

Thanks in advance

[stevegreen]

I always use ISO as a balance. I generally set the aperture first so I get the correct depth of field, then the shutter speed. If the shutter speed is below what I can hand hold (based on focal length multipliers and available light) then I will up the ISO to increase the shutter speed.

I always try and keep ISO as low as possible and this is the general rule, higher ISO = higher noise. As for the Nikon's Auto ISO I can't say as I use a Canon without that feature.

[springtide]

Auto ISO can work fine, but you just need to know it's limits. It will generally pick a shutter speed that can be handheld with the length of the lens and automatically pick the ISO to match.

Some Auto ISO settings allow you to set upper and lower limits, but not sure if the Nikon allows this or not.

This is fine, but the camera is making decisions for you that might be not what you want. i.e. you might be taking photos of fast moving subjects which you want to freeze the action as well as controlling the aperture, or you might actually want to blur the background for flowing water etc.

So, I think it can be useful but it also might make decisions you prefered it hadn't.

[py6km]

I think you can trust the auto-iso on the Nikon - it's a great feature. You set an upper limit for it, and a minimum shutter speed. If the shutter speed necessary to achieve 'proper' exposure cannot be met at a given aperture, the auto-iso will increment the iso value until proper exposure can be achieved, but it will never go above the maximum, and will always keep to the lowest iso possible. It's far better than the crippled implementation in my 40D.

[dg77]

Like steve I usually work out what aperture I want to use first, then set the shutter speed knowing that I'm hopeless at hand holding (even with IS lenses) at anly slower than 1/125.
If the cameras light meter is telling me I need to go slower I bump up the ISO.
I never use any auto settings, You will always get better photos if you keep the camera in manual.

[stevegreen]

Originally Posted by dg77

You will always get better photos if you keep the camera in manual.

.........and expose correctly