Mastering Focusing: Page 2
At its simplest, when using autofocus mode, focus is locked when the shutter-release button is pressed halfway. The LCD screen or electronic viewfinder indicates when – and sometimes where – focus is locked. A visual indicator in the viewfinder confirms when focus is achieved, and this will change colour. Alternatively, you may hear a beep when the camera is focused.
There are various types of autofocus:
Single-area AF is when the camera focuses on a subject in the particular area of the screen, depending on which AF point is selected – usually the central point. Once the focus has been set it stays locked at that distance until the shutter button is released, even if the subject moves in the meantime.
This method continually focuses on the subject, and is useful when shooting moving subjects. Selecting this option enables the camera to constantly focus on, and track, the subject, even with the finger on the shutter.
Nowadays, camera technology gives increased control to the user over the picture they are taking. Multi-area, or multi-spot, focusing is an example of this, by which we mean a set of points seen through the viewfinder that give the photographer the opportunity to focus on specific areas. Some cameras may have as little as three AF points in the viewfinder. Others such as Canon contain 45 selectable AF points, while Nikon’s new system pushes that even further to 51! With this method, the camera automatically focuses using one or more points, with the focus positions changing according to the position of the subject being photographed. The user has the option to let the camera automatically decide which point to focus on, or manually select it themselves.
There may be times when you’re feeling particularly creative, and just as blur can be created in an image using slow shutter speeds, so it can be achieved using focus. By deliberately making the subject out of focus you can create feelings of mystery, alienation, romance and much, much more. Simply use Manual focus mode to blur the subject as much as you feel necessary. You may want to deliberately miss the main subject and concentrate on another element in the frame or make the whole image blurred, creating an impressionistic painterly feel.
This method was the original method of focusing before autofocus. By rotating the focus ring, which moves the lens elements, the user achieves focus. This method is particularly useful for close-ups, or for low-light situations, where the autofocus fails. As the lens is focused, the image in the viewfinder will become clearer. Often a central split image in the centre of the viewfinder will enable finer detail to be focused. Some cameras allow the user to fine-tune the focusing manually while in the AF mode.