By utilising ISO as your key control with a digital camera, it allows you to shoot in a wide range of light levels and still achieve combinations of shutter speed and aperture that will produce successful images. The higher you go, the more there is a trade-off between quality of image and getting more light to shoot with.
Whilst in theory a large part of the ISO range available is usable, for most current Canon EOS cameras the workable range is between ISO 100 and ISO 6400. For slightly older models, this is up to ISO 3200. The full range of ISO settings available to you depends on the model you own.
Generally speaking, the full frame models offer a wider range and perform better at the highest ISO settings. There may be times when, to get a certain shot, you need to use the higher settings. The trade-off is digital noise.
ISO range
Low ISO – 50*, 100, 200, 400 – use in bright light with static subjects.
Mid ISO – 800, 1600, 3200 – use in overcast conditions or for moving subjects in combination with a fast shutter speed.
High ISO – 6400, 12800, 25600 – for low light photography or for moving subjects in poor conditions.
Ultra-high ISO* / 51200, 102400, 204800 and above – use for handheld shooting in very low light conditions.
*Available only some models – accessed via Expanded ISO settings in camera menu.
Auto ISO
Auto ISO works with shutter speed and aperture to provide a correct exposure. The camera automatically sets an ISO value which suits the light levels in which you are shooting. At the same time it aims to set a shutter speed that allows you to obtain blur-free results with a handheld camera and the lens in use.
It first appeared on Canon EOS digital cameras in 2003 and was limited to Basic zone shooting modes. On later cameras it is also available with Creative modes.
Auto ISO is especially useful where light levels change frequently.
Related terms
- Aperture
- Basic zone
- Creative zone
- Noise
- Shutter speed