SET TING UP AF FOR PORTRAITS
There are two key settings you need to select to ensure the AF system is optimised for portraits. These cover the AF point coverage and the behaviour of the AF once locked on the subject.
1 SELECT SINGLE- POINT AF: Use multi- point AF and you run the risk of the AF focusing on the wrong area. You want the subject's eyes to be as sharp as possible, so select a single AF sensor via the AF point selection button. Use the single AF point to focus on one of the subject's eyes, using one of these two methods: A) Use the central AF point, focus & recompose: With most cameras, the central AF system is the most precise, using the more sensitive cross- type sensor, as opposed to a line sensor, making it the best option to use. This is especially true when shooting in low light, when the extra sensitivity can make a difference. With this method, you focus on the eye by pressing the shutter button halfway, recompose, then shoot.
B) Select the AF point over one of the eyes: If you plan on shooting several frames without shifting the position of the camera or subject, then select the AF sensor over one of the subject’s eyes to save you having to recompose between frames. Take care to ensure you always have the AF point placed over the eye. This isn't the best option if you regularly shift your position or switch the camera’s from upright to landscape format.
2 Select single- shot AF: Your camera’s AF system has three main focusing modes, which control how the AF behaves after it initially locks focus. You want to select single- shot/ one- shot AF, usually designated as AF- S, S- AF or similar. Doing so ensures that the focus doesn't shift once you've locked focus on the subject's eye, even if you recompose the frame. You do need to be careful as if you or the subject move after you focus and before you fire the shutter, then you risk an unsharp result.