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Back Button Focus (BBF)

Wink11Wink11 Member
edited June 2014 in general photography
I've been trying out BBF and can't decide if I like it. Sometimes I nail the focus and others it's soft. Does anyone here use it? If so any tips or links where I can get a better understanding of it. I shoot mostly newborns but occasionally shoot family portraiture and weddings. So, still and moving subjects.

Thanks!

Comments

  • TrevTrev Moderator
    edited June 2014
    Jen,

    Back-button focus is where you assign another button other than the Shutter to focus, but you can also use the AF-ON button to hold, focus, and it stays locked so you can re-compose and then shoot numerous shots without having to keep focusing between each as long as you keep it depressed, have you tried that?

    I prefer to use that sometimes when I know I am wanting to shoot multiple images in succession without having to focus/reframe each time.

    Only drawback, it's for static subjects, moving switch to AF-Continuous (AF-C) on my D3s's it's located next to the lens mount, so so easy to switch with left forefinger with camera still up to your eye.

    http://digital-photography-school.com/back-button-focus/
  • MikeZMikeZ Member
    I love bbf. Especially under stressful situations and when you are tired after a long day at a wedding. Keeps me from shooting before I am ready too...lol
  • Haven't tried this. You don't risk getting out of focus pix? Ditto with the AF-on button and C focus?
  • Wink11Wink11 Member
    I think I really just need more practice, and remembering to switch to AF-C.

    I was told the BBF is great for when the bride is coming down the isle.
  • dmcdtcdmcdtc Member
    I use BBF exclusively...much better ratio of pics being in focus for me. Hold down the AF-On button while in AF-C and it'll track your subject nicely. Allows me to focus and recompose without worry as well.
  • Wink11, I am a big fan of back button focusing and use it exclusively. I set it up like this (on Nikon):
    1) AF Activation = OFF (which is AF-ON Only) - So the shutter button no longer triggers AF.
    2) Focus tracking with lock-on = OFF. Not all bodies have this setting. When set to a level other than OFF, it introduces a delay before adjusting focus if it senses a change in distance (ie. something briefly moves in front of the focus point). I don't personally find it helpful.
    3) AF-C priority selection = need to experiment with this. I often have it set to release but there sometimes are advantages in the other settings too (release+focus, focus).
    4) AF-C - Leave it there all the time. I don't understand what Trev said above about "Only drawback, it's for static subjects..." because when you use BBF if you want AF-S style you press AF-ON to focus and then release and then shoot, while if you want AF-C style continuous focus, you just keep holding AF-ON and shoot at will.
    5) With static or minimally moving subjects, I have the AF mode set to S (single point) and generally use the center point the most. With more active subjects, I sometimes flip over to D9 (dynamic 9 point) which will use your selected point but will consider the neighboring 8 points if the subject strays briefly.

    With a bride coming down the aisle, you would select your focus point and press and hold AF-ON while shooting. Shooting portraits, you can press AF-ON until focus is acquired, release it, then shoot. And for the static shots, you can choose whether to focus and recompose (center point on your target, press AF-ON and release, recompose and shoot) or select the appropriate point, press AF-ON, release, then shoot.

    I just find AF-ON approach a more deliberate way of focusing, and gives me the flexibility of single or continuous focus without needing to change my process. I got used to it pretty quickly. The only drawback is when you hand your camera to someone else to shoot a photo of you - you need to explain or change the setting before you give it to them. :)
  • ZenonZenon Member
    I have tried it several times and just can't get used to it. I half press the shutter, lock on and fire away. When done I release the shutter half way again which maintains focus lock until I'm ready to shoot again.
  • TrevTrev Moderator
    edited June 2014
    Nikonguy,

    Yep, correct I did get mixed up a bit, hurry to post before going out. :)
  • Neil vNNeil vN Administrator
    Just remember that in AF-C / Servo, the camera won't lock focus, but will keep "hunting" ever so slightly.
    For portraits, AF-S / Single is the best, in my opinion.

    Also, with AF-C / Servo, the auto-focus assist beam from your flash won't come on.
    So for me, using AF-C / Servo is useless in dark places such as wedding reception and wedding ceremony.

    I mention all this, because BFF is most often used with AF-C / Servo, and you "lock focus" by letting go of the back button.
  • Neil vNNeil vN Administrator
  • Great tutorial Neil. So, if you use AF-C you need to switch from focus priority (default for most for AF-S) to release priority. And back again. I've never liked C but will give it another try with moving subjects, my question is how do you know if your subject is in focus with C when there is no beep and the shutter's going to fire no matter what? Just relying on your good ole fashioned eyeballs?
  • Wink11Wink11 Member
    Great feed back! Thanks everyone. I'll try BBF again with these tips in mind.

  • ErinCErinC Member
    Hi Wink.

    I mostly do newborns too and rely solely on BBF. I had to use the shutter yesterday taking snaps at a picnic and it drove me insane! It means you can lock focus and take a few shots, then even recompose slightly without needing to reset your focus in between each shot.

    For NB I shoot in one shot, I've found it far more reliable. I also found with NB sharp focus is a really delicate balancing act - I occasionally underestimate how much effect a slight camera shake can have when you are in soooo close at F/2.8, both in terms of blur and shifting my DOF. The best tip I got recently was to pump my ISO before I drop my shutter - With NB we do that much post processing of the background and the skin that it can handle a little grain. But if you drop below 1/125 you'll start to notice camera shake a whole lot more. When I checked my EXIF on the shots that I didnt quite nail, all were 1/100 or below.

    One thing to consider with BBF though is your DOF. Because I am setting my focus separately to my shutter, there is more opportunity for me to move in between - at .5 metres from the subject and in F2.0, your field is razor thin - something like 2 cms. So thats something to be careful of. I deal with it by upping my aperture to somewhere around 2.8 - 3.5. You still get the lovely subject isolation but slight movements forward or back have less of an effect on your focus.

    I don't come across many other Newborn photogs here... Happy to compare notes if you'd like!
  • It is mentioned in Neil's links above, but if you use Nikon and use the back-focus button, Nikon VR lenses will not engage the VR.
  • dmcdtcdmcdtc Member
    From Neil's link above on Nikon D700 focusing modes...

    There is one small gotcha with using Back-Button Focus – the Vibration Reduction (VR) function doesn’t kick in with the AF-ON button, but only when the shutter button is pressed. So you might encounter situations where the VR hasn’t had time to settle before the shutter is fired. It’s just something to be aware of.


    So...just as clarification...if you're using AF-C with BBF, and you are tracking a moving object, does VR kick in while you are continuously tracking?

    When does VR actually kick in? While focusing or only when shutter is pressed? Is this true in all modes?
  • bobh665bobh665 Member
    edited June 2014
    Using BBF and AF-C by itself VR is not engaged. Holding the shutter button halfway down and using the BBF and AF-C at the same time VR is engaged. It works that way in all exposure modes. Heres an article by Thom Hogan explaing pretty much everything about VR.

    http://www.bythom.com/nikon-vr.htm
  • On the newer bodies (in the last couple years), VR does kick in with AF-ON.
  • dmcdtcdmcdtc Member
    Bobh665...great article. Thanks for the info.
  • Nikonguy, that is news to me. I only have the D700, so I didn't know Nikon changed this in newer cameras.
  • Wink11Wink11 Member
    Thank you everyone. I'm still practicing.

    ErinC, I'd love to compare notes!! I sent you a message. I look forward to connecting.
  • Big fan of back button focus. In my mind, focusing and pressing the shutter are two separate actions, and so should require two separate buttons. It's been my thought process, and when I first tried it years ago I adapted to it easily. At the same time, if you're not getting used to it, then I don't see why you should burden yourself in trying to do so.
  • I have a question about the timing. I haven't figured this out and the manual doesn't seem to say. If you press AF-ON to use BBF (let's say you are in C focus mode) do you release the button before firing the shutter or continue to hold it down? If you release it in C mode doesn't the focus point quickly change as the camera searches for a focus? If you press and release AF-ON in S mode will that point remain the focus point until you press it again or resume the half shutter focusing method? Or do you hold the AF-ON down the hold time?

    Saw this previous post, below, from NVN. May answer this but not sure. So, releasing AF-ON locks focus?

    Also, do you need to go into the menu and switch from focus priority to release priority?
    +++

    From NVN:

    "Just remember that in AF-C / Servo, the camera won't lock focus, but will keep "hunting" ever so slightly.
    For portraits, AF-S / Single is the best, in my opinion.

    Also, with AF-C / Servo, the auto-focus assist beam from your flash won't come on.
    So for me, using AF-C / Servo is useless in dark places such as wedding reception and wedding ceremony.

    I mention all this, because BFF is most often used with AF-C / Servo, and you "lock focus" by letting go of the back button."
  • Neil vNNeil vN Administrator
    Skipperlange .. it would depend on whether your subject is static or moving.
  • Thx Neil, I'm trying this with moving subjects.
  • Neil vNNeil vN Administrator
    Then don't let go of the AF-ON button. You want the camera to keep tracking the movement, as you trip the shutter.
  • So hold it down if subject is moving. In both S and C? Thx Neil.
  • Neil vNNeil vN Administrator
    No, not in AF-S / Single focus mode, when you're photographing a static subject.
    Different scenario.
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