Guidence with Auto-focus

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Archive 2004 · Guidence with Auto-focus

wbenson
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p.1 #1 · Guidence with Auto-focus

Wasn't sure whether to put this here or in the Pro section, but since I'm using a Canon 20D, and the traffic is greater here, I've opted for this forum.

Yesterday I took the day off work and took in the Eddie (a major Hawaiian surfing competition). I'm using a Sigma 300-800 F/5.6 zoom and the combination of camera/lens puts me right into the action (even though the surfers are a fair ways out). Anyway, I frequently ran into focusing problems. I'd keep the surfer centered as they approached take off and almost always get off a clean shot of the initial ride. But the next shot (in this case when the surfer was travelling down the face of the wave at a fair clip), often found the camera/lens searching for focus. It didn't happen all the time, but enough that it frustrated me and I'd like to see if there is something I could/should be doing differently.

I'm at work now, so I can't check my equipment settings, but if there are other experienced action photographers (and especially Surf photogs) who know the Canon 20D, I'd be interested in their advise concerning the best camera settings. What should I be using for AF points? Which AF mode should I be using? Is one setting best for moving targets, which are moving slightly closer but mostly across your field?

I did have a little better luck with using the multi-shot setting, I assume because it doesn't refocus on each shot (is that correct?), but since there is some movement I would think that you would want to refocus to ensure optimum sharpness??

Anyway, any thoughts, suggestions would be appreciated. I haven't had any time to look at the shots I took yet, but I took several hundred a couple weeks ago at Sunset beach and for the most part am very happy with the results. I just don't like missing the action while the camera/lens focus all the way in and then out again in order to lock the subject for another shot (I missed too many spills).

P.S. It is harder to keep the surfer centered on the second/third shot because they are moving, but the wave in the vacinity should be for the most part in the same depth of field.

Dec 17, 2004 at 01:39 AM

smjphoto
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p.1 #2 · Guidence with Auto-focus

Sorry I don't have much advise to offer. I was hoping others would jump in as I have similar questions especially shooting around water. I've been frustrated in shots with marlin jumping. With large swells, the background is walls of water. Also with some whale pictures, I get focusing on a wave just forward or behind sometimes. Both of these events happen quickly and in random locations, so response time is limited. I was hoping the 20D would help with faster and more accurate focussing, but I'm not sure which auto focus method is optimum.

Thanks for any insight anyone can give.

Dec 17, 2004 at 08:12 AM

uz2work
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p.1 #3 · Guidence with Auto-focus

If you are using the 9 point focus system in servo mode and if the background is busy, the camera can easily be tricked into focusing on something in
the background. This can easily happen even with the 45 point focus system on the 1DII. Waves on water are especially difficult. In shooting wildlife, I find similar problems in shooting a flying bird with a background of trees. For that
reason, with busy backgrounds, I switch to the center focus point, which I can
quickly due with the star button via custom functions.
Les

Dec 17, 2004 at 12:02 PM

PacAce
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p.1 #4 · Guidence with Auto-focus

Are you using AI-Servo? If not, try setting the camera to AI-Servo and use the automatic AF point selection mode. With this setting, the camera will first use the center AF point to get the initial focus lock. Once focus lock is attained, if the subject strays from the the center AF point, the camera will still be able to track it with the other AF points as long as the subject is covered by any of the other AF points.

Dec 17, 2004 at 04:05 PM

wbenson
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p.1 #5 · Guidence with Auto-focus

Thanks everyone for your help. On a positive note I post-processed about 50 images last night from the surfing contest and not a single one was out of focus. Whatever else is happening I can at least rely on this.... when the camera does lock and fire the AF is bang on. I love the pictures, just wish I knew how to market these because I really feel they are amazing (admittedly I'm probably a little biased).

Dec 17, 2004 at 05:27 PM

RDKirk
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p.1 #6 · Guidence with Auto-focus

PacAce wrote:
Are you using AI-Servo? If not, try setting the camera to AI-Servo and use the automatic AF point selection mode. With this setting, the camera will first use the center AF point to get the initial focus lock. Once focus lock is attained, if the subject strays from the the center AF point, the camera will still be able to track it with the other AF points as long as the subject is covered by any of the other AF points.

I find this to be true. The camera is evidently doing some intelligent "handing off" of the subject from one sensor to another when the focus has been locked.

Dec 17, 2004 at 05:59 PM

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