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AF-ON Button. Use it? Why?

Discussion in 'Sports Photography' started by Otter, Aug 19, 2008.

  1. I'm almost afraid to ask...

    Recently, in another thread, Chris (Aqualung) suggested to me to try the AF-ON button of my D200/MB-D200. He also pointed out a 15 page thread about its use. I read those 15 pages and, frankly, I don't get it.

    I don't see its value for sports shooting. Well, at least not for me.

    The last two soccer games I've used it. All I really did was hold the AF-ON button down with one finger and shoot with another. The MB-D200 makes it pretty easy to keep the shutter trigger partially depressed to keep AF-C going.


    Do you use it?
    What am I missing? Anything? Or is it just a preference kinda thing? I'm afraid I might be missing a key point about its use.

    Maybe one of you will help me 'see the light' so to speak. :smile:

  2. Muonic


    Jun 14, 2006
    I don't either.

    I've read that same thread several times, and it seems to me, that it is strictly a preference kind of thing. I've tried shooting action both ways, and I just don't see the advantage of one method over the other. Hopefully someone can enlighten me.
  3. Hi Joe,

    I use the AF on button all the time. . Dont know wether it helps but it's just a routine that I have got used to. . Seems strange not having it when using the D50 ..
    When I see the bike coming I just depress the AF button, all I then have to do is just touch the shutter release. . For me a lot of the time most bike races are incident free. . but I have to be prepared for anything at any moment . . Wether it speeds things up. . who knows. . ? but it works for me. .

    Others may say different. . this is just my opinion. .
  4. eng45ine


    May 11, 2005
    Chicago, IL
    I find that by using the AF-ON button, I am getting faster and more accurate focus speeds. I also get more keepers as compared to only using the shutter release button.
  5. There is a HUGEadvantage for most shooter to use the AF on button rather than the shutter release. Not sure why you did not get that from the mentioned thread.
  6. niknd501


    May 13, 2006
    Joe - I find that for sports like soccer it helps me from taking a bunch of unwanted shots. I had a bad habit of pressing the shutter release button when I didn't want to.

    Also it may be just my imagination but I think it tracks better than using the shutter button.

    It took me a little time getting used to it but now that I am it's just second nature.
  7. for portraits.. example.. you can focus on an eye and re-frame to center face without focusing on nose..
  8. nipprdog


    Jun 8, 2006
    Agreed, on all counts. One thing I haven't tried yet(may try it Saturday for soccer), is that trick that Randy learned from Mike, about turning the focus off from the shutter, so that the only focus is from the AF-ON button.
  9. kwf1


    Nov 15, 2007
    S. Florida

    I will take a shot at this, although I may not be able to explain it with words on a page very well, but here it goes.

    Let's take baseball for an example, you have AF-C on, disable the shutter function and use AF-ON button for focusing.

    The batter come to the plate, you want to focus on his face and not the bat, arm or elbow in front of his face. You prepare for the shot before the pitch,

    With AF-on, you focus on the face and when it aquires the focus you want, you then release it and wait for the pitch. You can then concentrate composition of the shot and the play and not have to worry about keeping the focus point where you want it. When you want to activate the shutter, you just press the shutter button, your camera fires on demand with no focus delay. You will not stand the chance that the camera refocuses on an arm, bat or the fence behind him when he moves his face.

    By the way, if you want to keep the AF-ON button depressed, then you will have AF-C constantly focusing. For the runner sliding in home plate, you keep AF-C pressed while pressing the shutter button, and you will have a series of shot in focus of the player sliding into home.

    You kind of get the best of both worlds, AF-C while keeping the AF-ON pressed, and AF-S when you release the AF-ON button after acquiring focus.

    With using the shutter pressed half way to focus and AF-C on,

    Your camera is consistently changing the focus point while the batter is waiting for the pitch. If the batter moves his head and you did not follow the move, you may have the fence in the background in focus. If the batter shifts his elbow in front of your focus point, then your camera will refocus on that and you will have a blurred or not as sharp face, especially when you are shooting at night at a high school field with terrible lighting, and your are forced to shoot at F2.8 to acquire a decent SS.

    Hope that helps,

  10. Joe,

    For me there is one distinct advantages. I can focus with the AF-ON button, release the button and still hold that focus at that time when i press the shutter button, it will not refocus (just exposure and shutter) ... so if for example you are anticipating a play on third ... piece of cake.

    The way to make that work is that you need to setup focus with AF-ON "only" .... NOT BOTH.

    I also recommend that you to turn the "SHUTTER RELEASE AE-L" to off. That way the camera is constantly adjusting for exposure during burst rather than locked on from first frame. ( useful in situation when player runs between sun and shade)

    Hope this makes sense.

  11. DJVCuda


    Jun 13, 2008
    Atco, NJ
    the AF settings dont play well with a 70-200 w/ vr... that must be triggered by the shutter half way down.
  12. Jim that's a critical part of making the AF-ON button useful. Focus/recompose becomes a "no-think" action.
  13. niknd501


    May 13, 2006
    Rolly - Is this a feature on the D200 or D300. . . I didn't know this. I looked for it on my d200 just a minute ago but couldn't find the setting. .

    If so - where would it be ?

  14. Hello Everyone,

    Thanks for letting me jump on board here. Im relatively new time line wise and dont have a broad range of experience in different kinds of shooting, but I have shot greyhound racing probably 150 times in the last year and feel like I can comment at least a little bit....

    I find this topic VERY interesting and useful!

    First off....I had been told by a couple of people that the AF-ON button deactivates the VR. Ive listened to my VR when turned on and it seems to be working when I am using the AF-ON button even when the focus from the shutter release button is turned off. Does that make sense?

    Oh, before I forget...can you tell me where the thread is that talks about the AF-ON button? I would love to read it. Thanks.

    When I zone focus at the track heres what I do:

    I pick a spot on the track before the race starts where I believe the dogs will cross at the angle and elevation that works best for a good shot. When the race is getting started I press the shutter release button halfway down and focus on that spot (greeen light on in "C" mode). Once the green focus light is on steadily, I press the AE-L/AF-L button and hold it with my thumb while my index finder is on the shutter relase button. As soon as the greyhounds approach the "shooting zone" I start firing at 8fps on my D300 and keep shooting until they are past the viewfinder. Normally, using this technique I will get a couple of sharp focused frames while the others are throw outs (of course this is a function of aperture, DOF etc.).

    Now, If I were to do the exact same thing, except this time.....disable the focusing of the shutter release button and pick my spot, focus with the AF-ON button, release the button and hold the camera in place and then start firing with the shutter release button as mentioned above, would that basically be doing the same thing as what I described in the previous paragraph?

    Oh, and not to go off tangent here, but 2 more points......

    1. Yesterday I switched from pre-focusing with the AE-L/AF-L button to panning with AF "C" and got pretty good focus %s using these settings:

    a. 51 pt. AF-Area Mode
    b. Matrix metering
    c. VR on

    I know this has a tendency to slow down the focusing speed of the D300, but I got some pretty good shots using this technique (go figure huh?)

    2. Have you folks experimented much with the focus interval setting? I think its "a4" on the menu (Im too lazy to go downstairs and get the manual), but I believe its "focus tracking with lock on". Does this mean that if you choose "short" vs. the default setting of "normal" that WHEN YOU ARE USING THE AE-L/AF-L BUTTON that the time it takes the camera to re-focus between shots is lessened? I believe the manual says that this is a feature that is used when someone might intersect the shooting line between the camera and the subject and you may want a longer focusing time in order to allow that brief interuption to not be considered in the focusing by the camera. In other words, the camera will ignore an object cutting in front of your subject. However, if you are pre-focusing and ARE NOT expecting an interuption it would seem to me that the "short" setting would be best. Also, when you turn it off completely does that allow the camera to focus even faster? And also, does this setting even apply when you dont use the AE-L/AF-L button?

    Sorry for all of this, but I thought I would just throw it out there to see what you think. I apologize for rambling and getting off subject a bit but I wanted to fully communicate some of my questions. Hope thats ok.

    My best to all!

  15. Tim White

    Tim White Guest


    What lenses are you using? AF-S? Seems like you are taking a number of steps to stop your gear from doing what it does well, which is track moving targets. Just track the dogs in AF-C (Single or Dynamic 9-point), either with the shutter half-press or the AF-ON button, and fire away. No need for thumb gymnastics and pre-focus points; I'd wager you're actually lowering your keeper rate with your current technique.
  16. McQ

    McQ Just your average, everyday moderator. Moderator

    Joe, it's a fair question, and no one who is reasonable can blame you for not understanding it from the other thread. It was a long-standing question for me, and it took me quite a while to switch over to using it. Some good answers were already given, with nice examples (Bert and Rick's were really good), so I can't add anything technical.

    I have to say it made many of my shots easier, especially for focus/recompose, and for the benefit of not accidentally fully depressing the shutter button while I was trying just to focus.

    I wouldn't go so far as to say it's a HUGE advantage, but it is enough of an advantage for me to keep using it vs. shutter half-press.

    Rolly, could you elaborate on the last part of your post, regarding AE-L being turned off? I want to make sure I understand it correctly.

    Even if this question comes up again, it's worth talking about, as this entire forum exists to help us all. Reminders are good. Isn't that why we're on the forum anyway?

    Keep on asking questions until you get it, and are satisfied, Joe! :smile:
  17. x272221713x

    x272221713x Guest

    Hmm interesting way of focusing, I've actually never used it with AF-on but I'll try it and see what happens..
  18. I have shot sports with canon's 1D series cameras for 14 years now and have always used the AF button on the rear only. My hit to miss ratio is usually around 85% or so, but if I shoot w/front focus, I guarantee it will certainly drop. I currently am still adjusting with the D3 because @ the moment, my hit to miss ratio is not quite as good. Be advised that this setup may not be for your type of shooting and it does take some getting used to.
  19. Hi Tim,

    I use the 70-200 f/2.8 for late afternoon and the 85 f/1.4 for nights.

    Thanks for the input and like I was saying....yesterday I got the best results by using VR on, 51 pt., shutter half press and panning. I have found though that when the greyhounds are coming directly at me that pre focusing does help a lot.

    Ive had some people tell me that the more the camera has to calculate things the slower it will focus, but yesterday I did pretty well.

    I think a lot of it has to do with learning how to keep the camera steady and improving panning technique......
  20. Hi Glen,

    I dont want to speak for Rolly, but Im pretty sure what hes speaking of is the c1 setting. If you set it at the default "off" then the focus will be continuous when you press the shutter release button halfway down in "C" mode. However, if you turn this setting on then the shutter release button will act like the AE-L/AF-L button in that it will lock focus and will not continuosly focus in "C".

    take care,

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