AF or not?

Discussion in 'Photography' started by kickillustrated, Sep 23, 2017.

  1. kickillustrated

    kickillustrated White Belt

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    What is your opinion about using auto focus for martial arts action shots from sparring or even competition? Does AF do a good service or is it just to hard to find a good focus point during moving action? I prefer to set a manual focus and it works better for me while I factor in a certain tolerance for depth of focus via a 4 aperture setting. So far this has given me sharper images for moving objects compared to AF of DSLR cameras.
     
  2. Bill Mattocks

    Bill Mattocks Sr. Grandmaster

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    Zone focus works as long as you know your depth of focus at your selected aperture and have good high iso if shooting digital.

    New cameras have good high iso but also good af speed.
     
  3. JR 137

    JR 137 Senior Master

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    How would you manually focus fast moving MA? Aside from aperture, shutter speed, etc. (which are all important), can you nail focus manually on a fast moving object?

    For fast moving stuff (with a Canon, but I'm sure others have it) I use AI Servo mode, and choose the center point. It locks focus on the center and auto adjusts as the subject is moving. I then hold the shutter button down and hope for the best :)

    I only get a few pics that are out of focus in each sequence that way. I'm no pro photog, so take my advice as you will. And I love my canon 85 1.8 for this. Focuses very fast, very sharp, has a great wide aperture, and the bokeh is fantastic.

    Now to get a camera with better ISO capabilities. My 40D gets too noisy above ISO 640. I'd love a 6D, but I'm broke.
     
  4. Bill Mattocks

    Bill Mattocks Sr. Grandmaster

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    Manual focus for fast moving MA is done with zone focus - predates most types of focus so not often used these days. But still quite valid.

    If you know your distance to the subject, and you know your focal length and aperture, you can calculate the distance (depth of focus) that will be in acceptable focus.

    Online Depth of Field Calculator

    It's tough, and it requires high-iso sensors or film to get small enough apertures to get focus zones that are useful.

    For example, say I use my Pentax K-x and I set my focal length at 135mm, my aperture at f/8 and my distance to subject at 20 feet. I will have a zone of focus that is 2.1 feet. Very slim.

    If I set my aperture to f/22, I can get 6.5 feet. Much more likely to catch the action in focus. But I'd better have a fast ISO on my camera and one that doesn't produce noisy garbage.

    [​IMG]8th Annual University of Michigan Ballroom Dance Competition by Wigwam Jones, on Flickr

    I took the above photo in a dark ballroom, using zone focus. Note that not all the photo is in focus. My camera at the time didn't offer good high-ISO performance, so I had to use a more open aperture.

    Here are some photos I took in 2008 at a Kendo tournament. Some used AF, some were manual focus.

    2008 10th Annual Detroit Open Kendo Tournament

    This is a manual focus photo from the Kendo tournament:

    [​IMG]2008 10th Annual Detroit Open Kendo Tournament by Wigwam Jones, on Flickr
     
  5. JR 137

    JR 137 Senior Master

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    So that's what that distance gauge/meter/whatever it's called on my lenses is for. Who woulda thunk it? :)

    Great pics! Your skills are impeccable.

    Edit: I utterly despise noise in my photos. It's currently the bane of my photography existence. If it weren't for noise (and less so a crop sensor), I'd be very happy with my 40D. I have zero realistic complaints about it outdoors where I can go 100 ISO. But the bulk of my shooting is unfortunately indoors. Bounced flash helps a lot and I've gotten pretty good at it, but it's only got so much range and gets aggravating to people during stuff like weddings, kids' plays, etc. And every time I try noise reduction during editing, my pics get blurred.
     
    Last edited: Sep 25, 2017
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