Okay just an introduction first. By default, the way we lock the focus is to push the shutter button halfway. But actually there is one feature that is often used pro photographers using the AF-ON button or (*) before, usually called “back button focus”.
What is a back button focus?
Back button focus is fitu autotokus by exploiting a certain button on the back of the camera, usually the AF-ON button or (*) and usually push with your right thumb. If the back of your DSLR camera there is a button with the inscription AF-ON or an asterisk (*), this technique can be used directly. If it can not be activated from the camera menu settings.
Why should the back button focus?
Back button focus particularly useful when we use continuous autofocus mode or tracking. In continuous mode is by using back button focusing, we can free up the shutter button to lock focus from the obligation. Remember, when in continuous mode, the intention is often desired to lock the focus, but what happened instead terpencet shutter so the camera takes full exposure.
The main advantage of autofocus with AF-ON button or (*) is that we no longer need to push the shutter button halfway. Simply by pressing the AF-ON button with the thumb to begin to lock autofocus and tracking follow moving objects. When you want to take photos, live we press the shutter button fully without removing the AF-ON button or (*). In future articles we will discuss thoroughly, what are the advantages of this technique.
How do I use the back button focus on DSLR cameras?
Not all DSLR cameras have the AF-ON button or *, but if the second button is not available we can activate it via the settings menu. Just an example, here’s how to activate the AF-ON button on Canon DSLR cameras:
Position the mode of operation in the “creative zone”: program mode – P, Aperture Priority – Av or Shutter Priority – Tv or Manual – M so that we can go to the Custom Function.
Click on the Menu button and use the Main Dial to select the custom functions, and then select Operations / Others, push the Set. Number functions here can vary depending on the type of camera. Canon 60D for example you choose C. Fn IV 550D-1 while the choice is C. Fn 9. (Check your camera manual).
This will open the Custom Functions: Shutter Button / AF-ON Button. To enable back button focus, select AE-Lock/Metering + AF Start and push Set.
Back button focus can now be used.
Okay good luck.