I have been focusing my camera a little differently lately thanks to a little used feature on my Nikon DSLR, the AF-On button. This button that hangs around the back of the camera doesn’t get much love from most photographers but I think if you give it a try you might find that it becomes your primary focus method.
What it does -
When the AF-On feature is activated in the camera, the focusing function is taken away from the shutter relaease button and assigned to this button on the back of the camera. When the button is pressed, the camera’s auto-focus system will activate and focus using whatever AF mode you have selected. It also means that pressing the shutter release button will now only activate the shutter, not the auto-focus.
Why you should use it -
You might have come across a circumstance where you are shooting a subject where there are obstructions that move between you and the subject but you still want to continue shooting with your subject still in focus. If your camera is using the shutter release button to focus you might have trouble maintaining focus because the obstructions are now in front of your focus point. If you use the AF-On feature, you can focus and then release the button and then take your picture with the shutter release button. You can keep taking photos using the shutter release and the camera will not try to re-focus until you press the AF-On button once again. This is also handy if you like find yourself focusing and then recomposing a lot. Usually this means that you have to hold the shutter release down halfway. With the AF-On button, simply place your focus point where you want it, focus the camera, then let go. No you can recompose and not have to press the shutter release button until you are ready to shoot.
It might seem a little weird to use this feature at first but I bet that once you start using it, you won’t want to go back to the old way of shooting.