AF-On Button for Focus Lock « Arthur Morris/BIRDS AS ART

AF-On Button for Focus Lock


I enjoyed a great morning at Morro Bay with two private clients, Bill Goodhew and Dwayne Marrott. The curlews and godwits and Willets and Western Gulls were all in fine form and the light was sweet. The afternoon, with a bit of fog thrown in, was fair to good. It got so foggy in the end that we wound up creating pleasing blurs.

I met the Canon Destination Workshop group at 7pm for our introductory session. Everyone in the group was nice and there were lots of good questions; everyone seemed eager to learn. Several folks borrowed 200-400 (with Internal TC) lenses. This blog post took 1 1/2 hours to put together and was published from my hotel room in Morro Bay, CA at 9:40pm.

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This image was created at Morro Bay on the morning of March 20, 2015 with the hand held Canon EF 100-400mm f/4.5-5.6L IS II USM lens, the Canon Extender EF 1.4X III, and the amazing Canon EOS 7D Mark II. ISO 400: 1/1600 sec. at f/9.

Center AF point (by necessity)/AI Servo Expand/Shutter Button AF, focus lock and re-compose. See below for details. Click on the image to see a larger version.

Surf Scoter in surf

AF-On Button for Focus Lock

Having come almost full circle, back to using Shutter Button AF more than 90% of the time, I now set the AF-On button to be my focus lock (AF-Off). To create the image above I focused with the shutter button, pressed and held the AF-On button to lock focus, quickly re-composed, and created two images in rapid succession. Using this technique was necessary as no AF point in the array could put the bird in the corner of the frame where I wanted it. Using rear focus would actually have been easier in this instance. But with the method above there is no need to switch from Shutter Button to Rear Focus AF when you need to re-compose.


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11 comments to AF-On Button for Focus Lock

  • avatar Geoff

    On the 7D2 and 1DX there is another way that you can have all 3 modes (Shutter button AI Servo, Back button AI Servo and back button one shot to do the focus recompose as you did with the Scoter)

    What you do is:
    1) set shutter button to Metering and AF Start and have Drive set to AI Servo.
    2) Set AF-On to Metering and AF start and use the INFO button to change the mode to One Shot
    3) Set * button to Metering and AF start and use the INFO button to set it to AI Servo

    This allows you to do shutter button focus in AI Servo any time you use just that button. AF-On button will do a ONE SHOT focus and if you keep it held down then when you trip the shutter it doesn’t refocus (shutter button is deactivated from focusing). The * button will work like back button focus like you used to do except that you can’t use it to focus and recompose because if you release it and press the shutter the shutter will refocus. But you would use the AF-On one shot mode for that anyways.

    Just a different way to skin a cat. Not necessarily better or worse but provides lots of options without ever changing settings.

  • avatar Frederick Correa

    Hello Artie,

    I enjoy the blog quite so. I only ask one favour and that is if you could provide the names of the birds or wildlife in your fabulous images. I’m in Canada and we don’t see many of the birds in our locale as you do. Every image that you post I somehow automatically search for the subject’s ID!


  • avatar Fain Zimmerman

    Does that mean your article on the rear focus tutorial no longer applies? I’ve just gotten used to using the rear focus button with the * instead of the shutter button and holding it down. It works very well for flight photos along with servo.

    • avatar Arthur Morris/BIRDS AS ART

      Not at all. If you use and love Rear Button Focus stick with it. What it means for me is that I am morphing :). I am not sure if this is mu brains response to using the 7D II more and more but I do not think so…..


  • avatar Jim Brown

    Just a question..If I set my focus to “one shot”, focus and re-compose, and my drive to “high speed continuous shooting” would that accomplish the same result? (i.e.. multiple shots of off-centered subject without re-focus and re-compose for each one). A Canon rep said “yes”. However the “yes” was somewhat hesitant in delivery.

    • avatar Arthur Morris/BIRDS AS ART

      Absolutely yes. But the advantage of both Rear Button Focus and my new way of doing things is that you never have to toggle back and forth between One Shot and AI Servo AF. artie

  • avatar Mouser Williams

    What is the advantage of this over using back-button focus to focus on your target, then releasing the back-button to hold focus and recomposing?

    • avatar Arthur Morris/BIRDS AS ART

      The techniques will yield the same results when properly executed. As I wrote, the advantage for me is that while using Shutter Button AF I do not have to switch to my Rear Focus setting…. artie

  • avatar Merv Lowe

    It’s the method I’ve been using.

    I tried back-button focusing but when I got part-time work shooting sport it was easier to use shutter button focusing for shooting constant action and I’ve just stuck with it.