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!
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
- 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.
- 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.
- In the camera menus, go to submenu “a” (Autofocus)
- 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)
- 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)
- Place the active AF point on your subject
- Press the AF-On button to acquire focus
- Release the AF-On button to lock focus
- Recompose and shoot
To focus continuously on a moving subject
- Place the active AF point on the subject
- Press the AF-On button
- Keep the AF-On button pressed to track focus while simultaneously pressing the shutter release
- 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.
The D4 works the same way as the D3. The difference is that in the D4 and D800 AF-ON activates VR, too.
Can you use this technique for shooting HDR images and if so would you have to keep the AF/ON button depressed until all images in the sequence have finished or not?. Could you walk me through the steps for using this technique when shooting an HDR sequence.
Thanks
When using the AF-On technique… What should I have my focus points set to? 39points, 9points, single point, ect. I have a D7000.
Thanks, Kenny
Kenny-
Use whatever is appropriate for the subject at hand. I use single-point whenever possible as it is the most responsive. However, if you’re tracking a moving subject and are having a hard time keeping the AF point on it, switch to one of the dynamic modes. Always try to use the fewest AF points as possible.
Thank you Jason, excellent description and instructions on camera set-up. I have been trying to figure out how to do precisely what you clearly described.
excellent tutorial, it helped me a lot
I’m using a simpler camera (D80) and it works great. AF-C priority goes automatically to release, whilst AF-S priority goes to focus.
Using AF-S if you focus, recompose and try to shoot while the AF point is not on focus it will not shoot (Error r06 ). This may be used as a ‘focus trap’, for example for shooting moving subjects, however for moving subjects I still prefer the technique you described (AF-C).
Great post, but I still don’t know how to set my D7000 as in point #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. ) I think AF-ON does not exist on it. Can you help me?
Thanks,
Mike
Finally, I got it. I have D7000 and the only button I could program as AF-ON is the back button (AF-L, AE-L). I wanted to do it with the Fn button, but I didn’t see the option AF-ON. Then I read one of the sites mention on this blog (http://everydayelementsonline.com/2011/11/how-to-back-button-focus/) and found the option. Great technique. I tried a few shots – not complicated and very reliable. I<ll try more tomorrow, outside, but I am sure I'll continue to use it. Thanks!!!
Mike
Thanks for the tip. Shooting a ballet recital this weekend and I think this will be a big advantage for stage shots.
great video covered most apart from what setting do you leave your focus in SPOT or AREA or do you have to change that as well
I use single-point AF unless I can’t keep the spot on a moving subject. Always use the minimum # of AF points that you can get away with for your needs.
Hi- I have the d5100. I set it up using the ae-l/af-l as my AF-ON button and switched my AF priority to release. So now should my camera work as you just described? If so then that is terrific! Thanks
It should.
Thank you for the video. I learned a lot! Just one part I couldn’t quite fully grasp if you don’t mind clarifying regarding setting it on Release priority. Won’t you get a lot of out-of-focus shots if you use that setting? Thank you.
Hi Jason,
I set this on my D800 but I hope I am doing this right. If I use it for a portrait shot, I use the AF-ON button set my focus point and release the AF-ON button, how come the green dot doesn’t show when I release to take picture? Am I doing something wrong? I understand for tracking a moving subject I must keep it pressed ( AF-ON) button. I set it up like in the video, is it different for the D800?
Thanks,
Rich Ramirez