Mastering the AF-ON Technique with Nikon DSLRs

On the rear panel of Nikon’s high-end DSLR bodies, including the D300, D700 and D3 series cameras, you’ll find a little button marked “AF-On.”  It seems kind of redundant to use this button for focusing when a half-press of the shutter release does the same thing.  Actually, I’ve found that setting the AF-On button to be the only way to activate AF is the best way to operate my Nikon’s AF system, but it requires a few set up steps and a little practice.

Why should you use the AF-On Only Technique with your Nikon DSLR?

The idea behind setting the AF-On button to be the only way to activate your Nikon’s autofocus system is simple.  Doing so allows you to set the camera to continuous-servo AF (AF-C) mode permanently, while still being able to get the benefit of focus-lock like you do in single-servo (AF-S) mode.  This means that at any time, you can switch between a focus/recompose/shoot style of photography (portraits and landscapes) and continuous subject tracking (sports & wildlife) without having to change camera switches or menu settings.

Also, with this technique, you decouple VR activation (half-press of shutter release) from AF activation.  That means you can be tracking a subject with AF and only engage VR when you want to.  This technique can save battery life in your camera!

Photoshop & Lightroom Guides by Jason Odell

How to set up y0ur Nikon DSLR to use AF-On as the focusing mechanism


The AF-On button is located on the back of most professional-level Nikon DSLRs
  1. Verify that your camera has an AF-On button.  If not, you’ll need to set up the AE/AF-lock button in the custom menus to use it as the AF-On button.  In the Nikon D90, this is custom setting f4.
  2. Set the camera’s AF servo mode to Continuous (AF-C).  This is done through the switch next to your lens mount, or via a custom menu setting. D90 users: hold down the AF button on the top of your camera, and turn the Main Command Dial until AF-C is displayed in the top LCD panel.
  3. In the camera menus, go to submenu “a” (Autofocus)
  4. Set custom setting a1 (Continuous Release Mode) to Release Priority (in the D90, this is already set for you when you choose continuous servo AF mode)
  5. Find the custom setting for AF Activation (a5 on the D3s) and set it to AF-On Only. This step is not necessary for the D90 and other cameras, as it is already set up by custom setting f4.

Now you’re all set up and ready to go.

How to use the AF-On technique in the field

To emulate single-servo mode (focus/recompose/shoot)

  1. Place the active AF point on your subject
  2. Press the AF-On button to acquire focus
  3. Release the AF-On button to lock focus
  4. Recompose and shoot

To focus continuously on a moving subject

  1. Place the active AF point on the subject
  2. Press the AF-On button
  3. Keep the AF-On button pressed to track focus while simultaneously pressing the shutter release
  4. Remember to initiate the VR system (if your lens supports it) by half-pressing the shutter button prior to releasing the shutter.  Remember, VR takes about a half-second to stabilize, so you’ll want to anticipate your subject.

Now that you understand how to use the technique, you’ll want to spend some time practicing.  It usually takes about a day of shooting in the field to get used to the new technique.  Once you know how to use it, the AF-On only method of focusing will help you get more “keeper” shots.

164 thoughts on “Mastering the AF-ON Technique with Nikon DSLRs”

  1. Extremely useful, particularly the points on the software not recognising where you originally focussed with recomposition as this can really confuse you.

  2. Thank you for this incredibly clear, well explained tutorial. I already had my camera set up to bbf, but I was struggling with focus issues at almost every session so I began to question my set up, and of course my technique also. Verifying my set up, I know know that my issues most likely either related to dof (I’ll try shooting at a safer f stop instead of fairly wide open) or my camera is back/front focusing which is something I guess I have to google next :/

    Thanks again!

  3. I have found this setup frustrating at best. I realize a LOT of photographers adopt BBF…. However, I use a tripod and trigger quite often, so the trigger focus is disabled with this setup. I could set manual focus, but that leaves me no ability to move away from the camera with the trigger…

  4. You have some perfectly valid points here. There will always be times when the traditional focus operation is desirable, such as if you are shooting one-handed over a crowd, or in the circumstance you describe.

  5. I followed your settings on my d7100, and am able to successfully press bbf, release and recompose and then click the shutter for an in focus shot. But am having trouble holding in the bbf and then tracking a moving object, seeing the center square or any square for that matter light up red and then clicking the shutter.

  6. Hi Nicole-
    When using BBF, focus tracking (activation) occurs when you hold down the back button. The AF points do not remain lit while focus operation occurs. They briefly illuminate in the viewfinder to allow you to know which one is active.

  7. Hi Jason, really helpful video. When shooting in single servo should the bb remain depressed when recomposing and depressed when pressing the shutter?

  8. If you use single-servo, you’ll need to keep the back button pressed to allow the focus to stay locked and the camera to fire, assuming that you’re set to focus-priority release mode.

  9. Why, when describing the technique, under “To focus continuously on a moving subject”, at point 3, do you write “while simultaneously pressing the shutter release”?

    (I presume this actually means, “while simultaneously HALF pressing the shutter release”?)

    But anyway, surely with the technique set up, just keeping the AF-On button continuously pressed will track focus? Simultaneously half pressing the shutter release will not change anything?

    (And indeed, you then go on to remind us to half press the shutter release to stabilise VR, which you wouldn’t have needed to remind us to, if we were half pressing the shutter-release.)

  10. To track focus, hold down AF-On. Half-pressing the shutter release activates the meter but won’t do anything else in this mode.
    In newer cameras (D4/D800 & later), the AF-On button activates VR as well.

  11. Thanks Jason, Your video wa svery useful, it is the only one I found that gives the tip of changing AF-C to release only. Also battery life saving tip too, awesome!!

Leave a Reply

Your email address will not be published. Required fields are marked *

11 − 1 =