Changing the ISO is easy; working out when to do it and what to change it to is the hard part
There are so many ways to change the exposure on your Nikon D-SLR that it’s easy to get lost on a sea of possibilities. It becomes simpler when you think of the ISO setting simply as a means of getting the shutter speed you need. Here are some examples of what we mean.
At night on a tripod: ISO100
Always use a tripod for night shots when you can, because when you’ve got the camera locked in position you can use any shutter speed you like – and this means you don’t have to increase the ISO and risk noise, even if your exposures run into many seconds.
Snapshots after dark: ISO1600
The latest Nikons can get great shots even at really high ISOs, so it is perfectly possible to shoot handheld indoors and after dark. But you will need a fast enough shutter speed to avoid camera shake, so try ISO1600 to start with, or use the Auto ISO function.
Low light sport: ISO6400
The problem here is subject movement. Sports are fast moving and you’ll need a fast shutter speed of 1/250 sec or 1/500 sec to have any chance of freezing the action. This means you may need a very high ISO indeed – but that’s better than blurred pics.