Autofocus techniques

Discussion in 'Sports' started by randrew1, Dec 15, 2016.

  1. Now that the basketball season is underway, I'm shooting games frequently. The main reason for discards is focus errors. I understand this is typical. I'd like a discussion of what works best. Here's what I've found:
    • I use the center spot only.
    • After reading an article about back-button focus I tried this technique. Focus errors increased.
    • I got a handgrip/battery pack to make it easier to shoot vertical (basketball is a vertical game). Focus errors dropped. I hadn't expected this. I'm wondering of the feel of the shutter release makes a difference. I also had fewer slanted shots that needed to be rotated a few degrees. I expected this.
    What other techniques have worked?
     
  2. Ron,
    hi.
    The usual reason for my focus errors in basketball (in particular but applies to any sport) is a player/ref running through the frame.
    I use the AF-button on my Nikon for back-button focus, for a Nikon this works best with Continuous focus (as opposed to Single shot mode).
    Your manual/an internet search for your camera should have plenty of answers as to how to get the best focus results - there will probably be lots of menu items to tweak. But also bear in mind the focal length of your lens (the longer the lens the higher the shutter speed to get sharp shots) and the light levels in the hall where you are shooting - if it's dim then it won't help your autofocus.
    Regards
    andyc
     
  3. Shooting hockey I've noticed that the back button focus results in more missed shots, probably because my thumb knocks my cheek and eye slightly away from the VF and I don't place the focus point accurately on the subject.
    Using the 'one-up' center point (the AF point one above the center point, to preferentially focus on faces) with the "AF expansion" cross-hair pattern (Canon) works well as long as:
    1. I keep the point on the player of interest, and
    2. I zoom out a touch as needed to make sure I get the entire scene as visualized.
    As far as other settings, I'm still experimenting with AI servo (Canon 7D). It seems to work well, as long as I do as above with the focus point.
     
  4. I also use the top AF point and AI servo
     
  5. Don't zoom in tight.
    This allows you more room to put the center focus point on the player.
    But watch out where on the player you put the focus point. AF does not work if it has nothing to focus on. So you need to put it on his face or the number on his jersey, or something else with contrast.

    If the player is coming towards you, AF-C and predictive AF. The problem is as the player is headed towards you, he can travel maybe a foot between when the shutter releases and the camera takes the shot. Enough at close distance to be out of focus.

    Watch for when the player is in one spot for a second, then shoot. That pause is what we used when shooting with manual lenses.
    Sometimes we zone focused, using depth of field (DoF). Rather difficult with today's lenses that do not have a DoF scale on the lens. But usually in the dim gyms, we were close to or at max aperture, so this did not happen very often.

    gud luk
     
  6. I don't use a grip. It makes an already heavy camera even more heavy.
    It just takes a little practice to hold the camera vertical.
    • Left hand supports the camera
    • Right hand just rests on the grip and fires the shutter.
    I easily shot 4 sequential high school basket ball games, a quad.
    However my senior citizen feet did not like it, they HURT. So I now limit myself to 2 sequential games.

    In my case I tend to tilt the camera for 2 reasons
    • #1, my left and right eyes are rotationally out of sync. This means if I position the camera with my left eye, which is watching the entire scene, the camera is slightly tilted. If I frame through the viewfinder, I can level the image.
    • #2, If I zoom a lot, the weight of the camera tends to cause me to tilt the camera to the right, to bring the weight OVER my right hand, where I can support the weight of the camera easier. Yes, very wrong, but that is what sometimes happens, when my left hand is working the zoom ring, and not fully supporting the camera+lens. This is why in the old film days, I used a pistol grip under the camera. The weight was balanced over my right hand.
     
  7. Yes this is an old thread, but the questions and answers are still relevant.

    For tilting.
    • Turn on the grid display in your viewfinder, then look at the stuff in the gym (corners, pipes, columns, etc), and align the grid with one of those. Check often, and it will help to keep you level.
    • On some cameras (like my D7200), you can turn on a viewfinder leveling indicator. You can't use it all the time, cuz you are tracking the subject, but it will help keep you aware of when you are tilting the camera.
     

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