We take autofocusing for granted. Lift an EOS camera to your eye, partially press the shutter button and the viewfinder image snaps into focus. But it wasn’t always so. With most pre-EOS cameras, focusing is done manually by turning a ring around the lens barrel. That sounds quite primitive by modern standards – but it does have one big advantage. It puts you in total control of the focusing. You decide on which part of the subject you want to focus. If the main subject is not in the centre of the viewfinder frame, it is easy to move the camera slightly to bring it to the centre, focus, and then recompose the image. Focusing is aided by a split-image rangefinder or by microprism dots that disappear when the subject is in focus.

It is possible to focus most EOS EF lenses manually, but the focusing action is shorter and less smooth than that of the earlier FD manual focus lenses. Most photographers rely on the AF (autofocus) system. Over the years Canon has improved and enhanced the AF system in EOS cameras to make it easier to get the results you expect. There are also techniques you can use to retain a greater degree of creative control.