Back-Button Autofocus  

Back-Button Autofocus

Back-button autofocus—a large number of photographers love it, others have no idea what it is. Most photographers use the shutter to focus. Back-button autofocus is found on many DSLRs. A button on the back of the camera is conveniently located where your right thumb falls when you hold the camera. This button takes over the job of focusing when you set it in the custom menu. Instead of pressing the shutter halfway down to activate autofocus, press your thumb on the back button. The shutter button is still used to make the photo.

There will be an adjustment period before you feel comfortable using back-button autofocus. Most photographers pick up a camera and innately use their pointer finger to acquire focus and release the shutter. Since the thumb will take over the task of focusing, deliberate thought has to be put into the process. The primary reason photographers stick with shutter finger focus is that back-button autofocus doesn’t feel comfortable in the beginning. Given the learning curve, photographers stick with the traditional method and use the shutter. If you dedicate time to adopt it, there are some advantages. I offer the following for you to think about to see if the scenarios fit into your shooting style. If they do and you’re willing to invest the time to get used to back-button autofocus, there are advantages—you make the decision!

Back-Button Autofocus

Off-Center Subjects: Back-button autofocus allows the photographer to lock focus anywhere in the picture, recompose the shot and then press the shutter to make the picture without having the camera try to refocus. As long as the subject and photographer don’t move, autofocus remains fixed at the locked distance. Traditionally, the photographer can lock focus by pressing the shutter halfway and recomposing the image, but this must be repeated for every picture. An alternative is to move the active focus point over the off-center subject. What method works best for you?

Obstructions: Moving subjects can be a nemesis to autofocus. Since continuous or servo mode autofocus is used for moving subjects, if something gets in the way of the subject, the autofocus system may try to lock onto the obstruction. With back-button autofocus, you can temporarily remove your thumb from the focus button and keep taking photos of the primary subject using the shutter button.

Manual Focus Switch Isn’t Needed: When you’re out in the field, there may be times when you have to use manual focus. For instance, the situation may dictate you don’t want the lens to refocus every time you press the shutter. This involves switching the focus method either on the camera body, the lens, or both. If you use back-button autofocus, you never need to activate these switches because the pressing of the shutter no longer controls focus.

Back-Button Autofocus

Sports: Lock the focus and wait for the action. Let’s use the example of a baseball game and you have two cameras going. Use your long lens to lock focus on second base for the dramatic double play or slide into the base. Set the long lens body to back-button autofocus and let the action happen right at the base. If the traditional method of shutter release focus is used while you track the subject, the movement of players may fool the autofocus and the entire sequence may be lost. If back-button autofocus is already locked into that point on the base, when the action is peak, focus is guaranteed.

Macro Benefits: Many macro photographers use a method of focusing where they rock back and forth to obtain sharpness. Because depth of field is ultra critical in macro photography, it’s imperative that the focus point is strategically placed. With back-button autofocus, it’s easy to get the focus in the ballpark and then use the rock back and forth method to massage the precise point you want sharp. With the traditional shutter release method, unless you keep the shutter button pressed halfway down, the focus won’t lock.

Back-button autofocus may or may not work out for you, but you won’t know unless you give it a try. You may want to incorporate it for just the circumstances where it makes sense. Certainly, there are times where it’s advantageous, so use it for those times. To set back-button autofocus on your camera, go into the custom menu and navigate to FOCUS. Set it up where you remove focus capability from the shutter and dedicate it to the thumb button on the rear of the camera. If you decide it’s not for you, reset the camera to the traditional method.

Visit www.russburdenphotography.com for information about his nature photography tours and safari to Tanzania.

Photography is what motivates me to move through life in a positive way. Photography is ͞All About The Light͟ and it’s the first thing I seek out before I press the shutter. Optimally, I pursue great subjects in great light, but if there’s an ordinary subject in great light, I still press the shutter. I love to share the photographic knowledge I’ve accumulated and I hope my enthusiasm is contagious so I can motivate others to feel the same way I do about my photography.

10 Comments

    Thanks for the article. I appreciate you going over the basics on occasion such as the back button focus. I’ve never used it because I thought it was more complicated than it was. Silly me!

    Thanks for the article, however back button auto focusing must have some disadvantages as well, and I was looking for what they were, hence the information provided is incomplete.

    Aside from the learning curve, the biggest drawback I’ve found is when someone volunteers to take my husband’s and my photo together at some scenic landmark. I lock the focus, hand them the camera and sure as God made little green apples, they’ll take a step forward or back! If I try to explain that it’s on back-button focus, I usually get a completely blank look.

    Thanks for the comments. BBAF is not for everyone. If you try it and like it, great. If you choose to use the shutter, that’s great too. The most important thing is, whichever system you use allows you to capture great images, that’s the best one for YOU!

    I’ve used back button focus intermittently. Could you please clarify the procedure once you have the back button focus set up for the following situations:
    1. Object that is not moving and want to re position object in better location within frame. As I understand you push back button to lock focus, take thumb off, re position, activate shutter.
    2. Object that is moving – push back button focus, lock in the focus, have focus setting on continuous (C), continue to push back button focus while object is moving and shoot away.
    Do I have this right? Thank you.

    Thanks. I have another special condition that has always been a problem with locking in the focus with movement. Here’s my example. Wildebeasts jumping over nile crocodiles. There are a line of wildebeasts jumping over the croc. I want to get the wildebeast/croc shot. How would you use the back button in this situation? Or would you set up a manual focus on one of the wildebeast/croc jumps and then wait for the next wildebeast/croc jump? Thanks again.

    Ironic in that I’ll be photographing along the Mara in Sept – leading a 14 day safari in Tanzania!
    What I have done in the past is pick the wildebeest I anticipate will jump. I follow it while I have constant pressure on the button so it will continue to focus. Sudden movement makes it difficult for AF to catch up so if you see a wildebeest that’s already moving and ready to jump, AF then has a starting point from which to lock on. The same principle applies to a bird on a perch that suddenly flies toward the photographer – difficult for AF to lock on.

    Micheal, thanks for the article. I’ve never used it because I thought it was hard to use. I’m going to give it a try and is if I can get use to using the back focus button instead of the shutter button. Thanks again for the tip.

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