Manual exposure control

Get to grips with aperture, shutter speed and ISO for better results

Making an exposure – in other words, exposing your camera’s sensor to light in order to record a picture – can be achieved a number of ways. You can let the camera handle everything in Scene Intelligent Auto mode, for example, or you can set the camera to a semi-automatic mode such as Aperture Priority (Av), Shutter Priority (Tv) or Program (P) and get more involved. With Manual mode (M), you have control of the aperture, shutter speed and ISO in order to make an exposure and the camera won’t set anything.

Well, that’s not strictly true. If you want to, you can set the camera to Auto ISO and let the camera handle the ISO speed. But you’ll still have to be on your game when it comes to deciding the best combination of aperture and shutter speed to use to get the right effect.

Manual mode isn’t as convenient as shooting in one of the semi-automatic modes and then using exposure compensation to make pictures brighter or darker on the fly. To fix exposure errors in Manual mode, you have to remember to adjust one of the three key exposure controls – aperture, shutter speed or ISO. If you change the aperture, you’ll also make more or less of the picture sharp. If you change the shutter speed, then that can have an effect on the sharpness too – if the shutter speed is too slow then moving objects in the picture may appear blurred, or the picture may be blurred if you’re shooting handheld. The ISO setting is often the key to the right exposure, as it enables you to use a combination of aperture and shutter speed that would otherwise be impossible to achieve.