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Thread: What is the practical use of the 'autofocus' back button?

  1. #1

    Default What is the practical use of the 'autofocus' back button?

    Hi all,

    just wondering if anyone can share their experience on how this button helps in their shooting?

    Thanks

  2. #2

    Default Re: What is the practical use of the 'autofocus' back button?

    Quote Originally Posted by weeloong View Post
    Hi all,

    just wondering if anyone can share their experience on how this button helps in their shooting?

    Thanks
    ... by allowing you to disengage AF to maintain focus, or to lock AF, or to reset the selected AF point to the center one...

    Without a clue as to what camera system you're talking about it's hard to make head or tails of what you are saying.
    Alpha

  3. #3
    Senior Member edutilos-'s Avatar
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    Default Re: What is the practical use of the 'autofocus' back button?

    Quote Originally Posted by weeloong View Post
    Hi all,

    just wondering if anyone can share their experience on how this button helps in their shooting?

    Thanks
    I don't use it at all, but that's because of my preferred style of shooting.

    This article brings up a lot of relevant points, particularly if you use a 7D.

    How and Why I Use the Back-Button AF | Learning DSLR

    Here's another one:

    Andrew Yip Nature Photography Why you should use the AF-ON button

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    Member Zackt87's Avatar
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    Default Re: What is the practical use of the 'autofocus' back button?

    help u to af when u are on live view mode
    I'm just a photographer looking for my world~

  5. #5
    Senior Member cichlid's Avatar
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    Default Re: What is the practical use of the 'autofocus' back button?

    You can also check this thread out

    http://www.clubsnap.com/forums/gener...tton-user.html

  6. #6

    Default Re: What is the practical use of the 'autofocus' back button?

    Quote Originally Posted by Zackt87 View Post
    help u to af when u are on live view mode
    Ows? My camera doesn't need that button to AF in LV mode.

    The specific function of that button will vary from manufacturer to manufacturer, then also in what mode you are in and if you set anything custom in the menu.

    If you can't figure out a use for it, maybe you don't need the manual controls a DSLR can give.
    Alpha

  7. #7

    Default Re: What is the practical use of the 'autofocus' back button?

    This question has been discussed awhile ago. I uses it on my Nikon system all the time, except when I need to pass the camera to a stranger whom has no idea how it operates. You set it to perform AF and your shutter release to only release without AF. In this way, this will allow you to release the shutter without refocus all the time.

    The following as some advantages through my personal usage that I feel is useful.
    1) Allows recompose even in continuous shooting mode
    2) Useful in fast motion scenes such as sports, racing and fast moving subjects where you can you release the shutter without refocusing. Eg: In the event for soccer game when you can see a player is going to cut your line of sight when you are continuously focusing on another player further away, you can quickly release the AF button and the AF stops, the focus is likely still on the player when the intercepting player moves away. You can then capture immediately, or press the AF button again with less chances of focus hunting.

    There are some quirks of course, because the shutter release no longer requires in focus to release, there are higher changes of out-of-focus should your subject is not in focus when you release the shutter. You will need to depend on your hunch, or visually on the in-focus indicator found in the viewfinder to indicate that you are in focus before release the shutter. This is not so much a problem for a slow photography event such as landscape or event, but for fast motion event, there is higher tendency for OOF.
    D3S|N70-200|N24-70|N24-85|N50f1.4|N35f2|SB800|SB900|Yashica GS|S95
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  8. #8

    Default Re: What is the practical use of the 'autofocus' back button?

    prevent AF from hunting and u can snap even if focal point is not achieved with the lens on AF mode. [ better if your lens allows FTMF ]

    reduces number of presses on shutter button [ to hunt focal point ], thus lengthening lifespan of that button [ which is prone to fail always on canon xxD bodies ]

  9. #9
    Moderator rhino123's Avatar
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    Default Re: What is the practical use of the 'autofocus' back button?

    Quote Originally Posted by Zackt87 View Post
    help u to af when u are on live view mode
    Which camera brand are you using? My Canon focus as per normal even when I am using the live view.
    I am not a photographer, just someone who happened to have a couple of cameras.
    My lousy shots

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    Member Zackt87's Avatar
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    Default Re: What is the practical use of the 'autofocus' back button?

    Quote Originally Posted by Rashkae View Post
    Ows? My camera doesn't need that button to AF in LV mode.

    The specific function of that button will vary from manufacturer to manufacturer, then also in what mode you are in and if you set anything custom in the menu.

    If you can't figure out a use for it, maybe you don't need the manual controls a DSLR can give.


    Quote Originally Posted by rhino123 View Post
    Which camera brand are you using? My Canon focus as per normal even when I am using the live view.
    Flickr: Discussing Live View autofocus problem in Canon EOS 5D Mark II

    Canon 5D Mark II: Live View - YouTube (06:17 onwards)

    Im using 5D2; AF-quick mode
    I'm just a photographer looking for my world~

  11. #11

    Default Re: What is the practical use of the 'autofocus' back button?

    All my old 5D and 1Ds are set to back button for focus... mainly for easy lens manual override the and to overcome focus hunt. other then that I can depress the shutter anytime without the lens trying to focus thus missing the shot... but you have to practice and get use to it...
    Leica M4P/ M2 / Summarit 35mm f2.5 / Summicron C40mm f2 / Kobalux 21mm f2.8

  12. #12

    Default Re: What is the practical use of the 'autofocus' back button?

    Many thanks to all who have shared their exp and useful knowledge! =)

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