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Old Mar 24, 2006, 2:03 AM   #1
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AI Servo ~V~ONE-SHOT what is your opinion?

I have heard a little negative on both, I shoot sports and want to hear your opinion on what you use and the results. One negative I hear on AI-Servo is that not many of the shots are in focus. Do you agree with that? I will be shooting a track meet soon and need your advice.
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Old Mar 25, 2006, 10:41 AM   #2
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For sports the issues are a bit harder. It you shoot things that rarely moved then the answer would be easy (one-shot.)

What sports do you shoot? How fast do they move?
I shot wildlife and therefor the subjects are almost always moving. I leave it in AI Servo all the time. I view the tradeoff's to be this:
Do I miss shots because the subject moves while I'm waiting for the "perfect" moment/position?
Do I want to be continuously tapping the shutter so it shifts focus with the subject?


My answer is "yes" to the first and "no" to the second.
But I have redefined the * button to stop AF. So if I want to keep it from trying to adjust for movement then I can. I'd prefer to redefine that button to toggle AF modes, but there is no way to do that. I can do it on one of my lenses, but that is because it has buttons on it.

Eric
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Old Mar 25, 2006, 9:37 PM   #3
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What Eric said but, I haven't redefined the * button. In AI servo if a lot of pictures are out of focus, it is usually because I didn't wait long enough to get a lock on focus or I really didn't have the center focusing spot on the moving subject and it focused on the background instead. So, that is operator error.

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Old Mar 25, 2006, 9:41 PM   #4
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I shoot several track pictures today and used ai-servo. Seamed to work ok. I did have a large problem with shadows being way underexposed. Any ideas on how to get that better?
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Old Mar 25, 2006, 10:15 PM   #5
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What metering mode?? I would try using center weighted averaging. It's difficult to expose for highlights and get shaddows correct or visa-versa. Most people will expose for the highlights and adjust the shaddows in an editor. You can set your camera for manual exposure and adjust that way or use one of the other exposure modes and adjust the Exposure Correction (EC) to expose the way you want.

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Old Mar 25, 2006, 10:24 PM   #6
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Could you please post a shot that would best describe your problem.

I shoot with a 20d,70 - 200, 2.8, or the 100 - 400, 4 - 5.6, action, low light, competitive swimmers and after taking several thousand pictures, throwing away hundreds due toa lot of pics that were out of focus, I have come to realize that two settings play a very close part with one another and gettingthose tworight have been the difference of throwing away 2 or 3 hundred pics in a weekend of swim meets to maybe throwing away 80 to 100.

The two points I have found that work the best together for action is the "evaluative metering" and "center focus". These two together plus just knowing and getting better as towhen and where to shoot on the subject has made a world of difference.

For swimming, one factor that will throw off a focused subject is the water splash coming between the subject and the camera. I tried fixing that focus problem with "all points focus" andchanging the metering to "Centerweighted Average Metering" and in that setting most pics were trashed.

What is your metering set to?
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Old Mar 25, 2006, 10:25 PM   #7
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I was using center weighted and no adjustments. Here is a sample of what I mean.
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Old Mar 25, 2006, 10:30 PM   #8
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Old Mar 25, 2006, 11:17 PM   #9
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Do you understand how metering is done on cameras?
It wants to make the image gray - an "average" tone. It will want to turn white gray and under expose. It will want to turn black gray and over expose.
You have only two ways to control this:
- What metering mode you're using
- Exposure Compensation

The different metering modes tell the camera what part of the image to use as the basis for the exposure. What modes you have depends on your camera.
- Partial Meter or Spot metering means that it bases the meter of the entire scene on a very small part at the center of the image. Partial is a small area, but not that small. A Spot meter is a very small area.
- Center-Weight Average says that we'll base the metering mode mostly on what is at the center, but we'll still consider the rest of the image some (it doesn't matter as much, though.)
- Evaluative Metering is when it just averages the whole scene. Very simple.

If you have the 20D, you can read about it on page 71 of your manual.
I would start with Center-Weight Average and I bet that will help. The ground and building in the background is dominating the scene. The camera is basing the metering more on that on the figures. I bet that will help.

For example, if you wan to photograph someone wearing white, even with center weight average it will get it wrong. You'll need to use exposure compensation to turn it from gray to white (by increasing the exposure.) The same thing (in reverse) applies to people in black outfits.

But the reality is that the camera is only guessing at what the metering should be... you'll have to learn how it gets it right and wrong. And then use exposure compensation to correct its mistakes.

Eric
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Old Mar 25, 2006, 11:34 PM   #10
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I noticed in the exif that the camera was on average metering. My mistake I thought I had it on center weight. That would go with what you are saying. My Bad. Looks like I have a lot of photoshop ahead.



Thanks
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