Tech Talk: ISO setting
As summer approaches, you may find yourself shooting in many different lighting scenarios, including low light. For example, you might be photographing an evening party where there just isn’t that much available light. One solution is to turn on your flash. But if you don’t want to do that, you might opt for increasing the camera’s ISO setting. If you’re not familiar with the term ISO, here’s some help:
ISO stands for International Standards Organization, the association that developed this specification for film many years ago. As with film, an ISO setting measures how sensitive a camera is to light.
A lower number, 100 or 200 ISO, means that the camera is less sensitive to light than at 1600 or 3200 ISO. When the lighting is less than ideal, using a higher ISO setting gives you more flexibility in adjusting other exposure settings (such as aperture or shutter speed) to capture a well-exposed photo or freeze action. It also lets you avoid having to use your camera’s built-in flash.
This flexibility comes at a price, however. Making a camera more sensitive increases the strength of the signal from the sensor, akin to turning up the volume on your car radio. Yes, you’d definitely hear more sound, but if there’s any static or background noise on the radio, that will also get amplified. Likewise, in digital cameras: When you capture an image in low light with a high ISO setting, the camera may be forced to “guess” at details in the image, thereby producing specs of false color (called artifacts), also known as visual noise. This can degrade the quality of the image.
Some cameras do a better job than others with high ISO settings. Our Ratings (available to subscribers) tell you which ones to look for. When choosing a rated model, check its “Max. ISO with best quality” column, which indicates the highest ISO setting at which that camera can still produce a good-quality image without a flash. —Terry Sullivan