Digital Photography Tips: ISO And Light Settings

Step 1: Why we use different ISO Ratings

The reason for different ISOs was to cope with the different circumstances the film would be used in. Photographing fast moving objects requires a quick exposure to avoid a blurred image, so the film needed to be able create an image from the brief exposure to light it would receive. This would need a low numbered ISO. Equally, shooting in dark conditions needed a film that could create effective images from a long exposure, so would use a high numbered ISO. Due to the way it was made, high-numbered ISOs tended to produce grainier images than low numbers as the light sensitive crystals on the film had to be larger.

Step 2: ISO ratings on Digital Cameras

A modern digital camera comes equipped with ISO settings that recreate the effects of ISO film speeds. So instead of changing an entire film when your shooting conditions change - you just change the settings on your camera. Compact cameras will usually handle these automatically, while SLR's will have a series of modes that will influence the ISO, including a manual mode that let's you adjust it independently.

Step 3: Noise Reduction

Some cameras feature automatic grain reduction, also known as "noise reduction" to clean up images taken using a high ISO rating. However this setting can leave your images looking soft and inaccurate. If your camera doesn't feature noise reduction settings you can apply them later using image processing software like Neat Image.

Experiment with different ISO's and remember that if you're going to be doing a lot of long exposures, you'd be wise to invest in a tripod to ensure you eliminate the camera shake that can spoil this kind of picture.