USING THE * BUTTON (BACK BUTTON FOCUSING)
I frequently give this tip to SLR uses: Learn to use the * button on your camera! Some cameras like the 5D Mark II has the AF-ON button to do this.
The * button behind a Canon SLR
The * button (or AF-ON button) focusing is often referred to as back button focusing. Out of the box, all SLRs have the shutter release button do two things: focus and release the shutter (and also reads the exposure). So whenever you press that button, two main things happen. This works well because you use only one finger to lock focus by pressing the shutter button half way down, and recomposing if necessary. However, there are many advantages in separating the focus mechanism from the shutter release. Here’s what I can think of:
1. Easier to capture the perfect moment. Once you lock focus using the back button, pressing the shutter button will activate the shutter faster because there is no more focusing involved. This is very useful to capture the right moment for instance when someone is speaking, you want to concentrate on getting the right expression. If the camera has to focus everytime you take the shot, you lose time. Especially more so if the you’ve placed the person off-centered, out of the focusing points. So lock, your focus with the back button and just fire away.
2. Easier to capture moving subjects. Say you want to take pictures of your dog running towards you. You can set the camera to AI Servo to track movement and use the back button to lock your focus on your dog, while holding the shutter button down all the way to fire as many frames as possible. If you don’t do this, you’ll have to track and fire, and keep repeating the cycle all the time.
3. Easier to steal shots. Good for candid portraits when you want to shoot without holding your camera to your face all the time. You can chat with a stranger and still take good candid portraits. I do this a lot. I start talking to a stranger, pretend I’m playing with my camera and focus on his face and then bring the camera down, talk to him and fire away. Keep eye contact with him all time and he won’t realize you’re taking his picture.
4. Easier to take macro pictures. For macro shots, very often you’ll need to set your focus on the subject and then keep moving back and forth slightly to get the part you want to be in focus. You can’t do this, if the focus is with the shutter button.
5. Easier to avoid focus errors in moving objects. Say you’re shooting sports and you’re focusing on someone, another person walks across the frame. You’ll be able to stop focusing by lifting your finger off the back button momentarily and resume after the person walks out of your frame.
Using back button focusing makes your SLR perform like manual focus camera. Very useful to shoot moving objects because you can pre-focus on a spot and fire away when your subject reaches it. In the days when autofocus tracking was not that sophisticated, this was the way we shoot. So unless you have a fast camera like the Canon 1D series, you’ll probably want to try to do this too to get sharp images.
Check out your manual on how to set this. It’s hidden in the custom functions. Practice using this back button and you’ll see how much you’ll improve in gettting tack sharp images.
Themocracy
Hi, was wondering will you be conducting any portraits shooting course? will be really interested in that…thks
Hi Simon, yes I can conduct a course like that but I will need a minimum of 4 people. I can publicize this but if you have any other friends who might be interested, we can form a class. Thanks for asking!