Don’t dismiss this automated feature – it can save your bacon when you need to shoot quickly
In order to select the ISO sensitivity of your choice, you need to be using one of your camera’s more advanced shooting modes. Even then, you can select the Auto option in the ISO menu to let the camera handle the sensitivity. Here, the camera will set an ISO that will give a reasonably fast exposure for the lighting conditions.
Auto ISO is a useful option when you’re moving from outdoor to indoor locations and don’t have time to change the ISO manually. It can also turn Manual mode into a combination of Aperture Priority and Shutter Priority: once you select your preferred combination of aperture and shutter speed, the camera will do its best to maintain a consistent exposure by adjusting the ISO.
When you’re shooting in low light, there is a risk that the camera will select an ISO that’s too high, leading to noisy pictures. But you may be able to reduce the ISO range available to the camera.
MAX HEADROOM Take some test shots to determine the ISO at which image quality becomes unacceptable, then use that as a guide to the Auto ISO limit.
FURTHER OPTIONS Some cameras let you reduce or expand the normal ISO range, and even set a minimum shutter speed that Auto ISO will attempt to maintain.