How-to's

Back button focus for newbies

Keywords: auto_focus, focus, af_s, af_c, back_button_focus, af_mode_switching, wildlife, nature, moving_targets, mkhurder, bif, birds

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Have you ever been caught in one AF mode when you want the other? You try to switch from AF-S to AF-C so you can capture those birds in flight, but by the time you switch the flock has gone past or found a new perch. This has frustrated me in the past, so I sought out a solution. With a few settings you can use "Back Button Focus" which will simplify the process and eliminate the need to make that AF mode change.

I’m new at serious image making, so my advice would probably be better focused on new shooters.

I’d been taking touristy pictures my entire life until I retired and took the time to look at what I’d been shooting. Honestly, the results were mostly bad. I wanted to do better. About 2 years ago I stated taking Photography classes at a local college. Today, though still a beginner, I am making images and enjoying the process of learning how. The process has not exactly been painless and I’m still refining my techniques. None of the time I’ve spent learning has been wasted though and all of it contributes to better images.

When first starting out in photography one of my biggest bugaboos, if you will, was AF modes (AF-S & AF-C). When do I use which and must I really fiddle with all those buttons and dials to switch from one mode to another? Every time? What a pain! It’s a crap shoot hoping my fat little fingers will find the right buttons and dials to set, and I will no doubt lose track of my subject while making the changes. Sheesh! For me, simple is always better.

I’d tried shooting moving subjects in AF-S. It’s no fun and the results were rarely tack sharp. I recall a day when I first decided to shoot wildlife. I observed a bird sitting in a tree. I was in Single Servo mode, AF-S and I shot away. That was great until the bird moved. As quickly as I could find the right buttons and dials, hoping I didn’t lose the bird while finding those settings, I switched to AF-C mode so I could track that bird in flight and capture some wing work… but wait, the bird had settled again and then the camera wanted to focus all the time on anything at all but the bird. Then I switched back to AF-S. Dang! He was moving again. You get the idea. Granted, I was a rookie in over my head to begin with. I was not very well versed in my camera’s functions and settings either, but really… how do you find and do all that in a heartbeat? I got a few images of the bird… none very pleasing.

Shortly after that experience I was visiting the Nikonians Forums researching AF issues. With Mike Hagen’s, "The Nikon Autofocus System" book open in front of me (from Rocky Nook-Nikonians Press), I stumbled on a description of "Back Button Focus". I thought, "Is this it?" I did some research and found that I could set my camera to do the following:

- Set AF modet to "AF-C" and leave it there. Turning on "Continuous Servo Mode" sets the AF System to continuously try to focus if you’re holding down the focus button… hopefully you can keep your subject under a focus point.

- Set AF Priority Selection to "Release’ or ‘Focus and Release". "Release" sets the camera to go ahead and shoot even if camera’s AF System doesn’t think your shot is in focus. The idea is that you’ll have focused with the AF button before you push the shutter release that first time. "Focus and Release" forces you to be "in focus" before you can release the shutter that first shot. After that you’re in "Release" mode and it doesn’t care about focus again. The thought process behind this setting is as follows: If you wait for focus every shot once you’re tracking a moving subject it may not shoot at all. Get the first shot in focus and then release the shutter and go for it. With practice you’ll keep your subject in the frame and under a focus point or two retaining tack sharp focus.

- Set AF Activation to "AF-ON only". This assigns the "Auto-Focus" function to the "AF-ON" button only, located on the back of the camera body. Since it makes no sense to have two focus buttons fighting each other, using the "AF-ON only" setting removes the “Auto-Focus” function from the shutter release button on top of camera body. You can still use a half-push on the shutter release button to lock exposure, (see your camera’s settings). You can also set the “AF-ON” button on your battery pack to do the same for when you rotate your camera (Rotate Tall).

That’s it. You’re ready for "Back Button Focus”. There are other possible preferences, of course. Such as how many focus points to use, dynamic area, Group area, 3D tracking if you have it, Continuous HI, Continuous LO, etc. With the above settings alone, you can shoot using "Back Button Focus" and save yourself some button pushing.

The benefit of this method is best described using the scenario I used above with the bird in the tree. After setting my camera for "Back Button Focus" as described above, now when I see the perched bird, I can press the AF button, focus, release the button locking focus, compose and start shooting. I am effectively in AF-S mode without switching anything… even though the AF mode is set to AF-C.

When the bird takes off, I simply track the bird while holding the AF button down, continuously focusing and shooting away as he goes. I am now in AF-C mode and again I didn’t have to switch anything.

If the bird perches again, I lift my finger off the AF button and again I’m in AF-S mode. I now make wildlife images that I am proud to post. That’s partly because now there is virtually no hassle switching AF Modes.

The more I train the better I image!

NOTE: I use a D850 and your settings or the names of the functions may be slightly different. I have used the same setup on my D5300 and there were some minor differences in nomenclature.

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