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Old Apr 17, 2006, 4:13 PM   #1
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I am trying to improve my shooting technique using my 20D canon with several different lenses including the 70-200mm f 2.8 and the 85mm f 1.8. I primarily shoot high school sports--day and night games as well as indoors and outdoors and typically use either manual mode or shutter priority depending upon the variability of the ambient lighting.

I have tried using AI Focus and AI Servo Focus with both single and multiple focus points and haven't been able to figure out which provides the more reliable focus result. At times the intended subject seems well focused and other times quite soft, even out of focus. It doesn't seem to matter which focus mode I am using or if the focus point is on the subject.

With action shots it is some times difficult to ensure that the focus point is dead on the intended subject and poor focus could the result. I expect that. But I am surprised to have focus issues in well lit situations when the focus point is on the intended subject especially if the lens is not wide open, ie the depth of field is not razor thin.

Does anyone have any recommendations that might improve the number of properly focused subjects in my action shots.

As an aside, in trying to learn more on about focusing properly, I consulted the 20D manual. The discussion on "Lens' Maximum Aperture and AF Sensitivity" (pg 68) is confusing. Does anyone understand and can explain what the manual is saying?

Thanks for your help.
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Old Apr 17, 2006, 8:21 PM   #2
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Which AF point you use will absolutely make a difference in your results with the 70-200 f2.8 lens.

The center AF point is a full high percision cross-sensor when using an f2.8 lens. And that should make it more responsive and more accurate. If you have a choice, use the center AF point only. (Your subject and desired compositions might make that impossible.)

The Canon AF system focuses on the closes point under an active AF point. So if you use all AF points on a sideways person and the shoulder is under one AF point and the head under another it will focus on the shoulder every time. So you have to be aware of this.

Don't use AI focus. It is the worst invention of all time. Do you really want the camera choosing when the subject has moved enough to refocus and when its stationary enough to stop focusing? For me, it kept blowing it. I only use AI Servo and I'm very happy. I just program the * button to stop AF (but keep doing AE) and if I want to keep the focus I just press it with my thumb.

To really tell what is going on in the images that didn't work you'd have to post a crop of the image without reducing it. It could be motion blur on your part, it could be subject blur (all due to low shutter speed) or it could be a miss-focus by the camera. I can't speculate without seeing an example.

I don't have the 20D manual any more, but my guess about that section is:
the camera focuses at the max aperture of the lens (f2.8 in the lens mentioned above) but takes the picture at the aperture you set it at. The center AF point is more accurate with an f2.8 lens (note, you don't have to shoot at f2.8 to get the benefit!) I bet that is what they are talking about.

Does that help?

Eric
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Old Apr 17, 2006, 9:05 PM   #3
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Thanks for the info eric.
I will avoid AI focus mode from now on.

Also your conclusion about what the manual is trying to say seems to be correct now that I understand about the center focus point.

I should have mentioned that the shots that really concern me are those take using high shutter speeds, 400-1000, to minimize motion blur, mine or the subject's. I generally shoot everything at greater than 250th and in daylight use the above range if possible.

Re yyour comment:
"I just program the * button to stop AF (but keep doing AE) and if I want to keep the focus I just press it with my thumb."

Could you explain how to program the * button to stop AF?

I will be shooting again in a few days and will try to capture a shot of the problem and send it.

Thanks
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Old Apr 18, 2006, 10:16 AM   #4
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Glad I could help. It does seem odd that you'd get blur at 1/400 to 1/1000. It is possible, but unlikely. Depends on what sports the kids are playing. Something like baseball should be ok except at bat... then those arms are swinging fast. But I don't photograph kids, so I wouldn't know from first-hand experience.

There is a custom function on the 20D that lets you do it. I don't have my manual for the 20D right now, so I can't be sure. But I believe it is custom function #4. Read about how to set them in the 20D's manual.

Eric
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Old Apr 18, 2006, 10:40 AM   #5
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Here's a couple more suggestions... I shoot sports/post shots on my site to sell. I use aMark II N and a 20D.

For situations where the light doesn't change much (indoors). I use a 18% gray card and set a custommy white balance, select ashutter speed and f/stop and leave it. This allows the camera to just focus and not have to do any AE processing every time you press the shutter. This is more important on the 20D! (The Mark II N hasmultiple processors for AE/focusing and the 20D just can't compete with this camera IMHO).

I reprogram the '*' button to do focusing and the shutter to just fire the camera.

Joe


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Old Apr 19, 2006, 12:53 PM   #6
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Joe and Eric
You both suggested using the custom function 4 to reprogram the * button to do auto focus. I have not tried that yet but for the quick reaction needed for sports shooting, isn't that a bit cumbersome to execute, ie, using your thumb to push the * button and also pressing the shutter with your finger--I sometimes have trouble walking and chewing gum at the same time so it will probably take some practice for me to be able to do that.
As you are both aware it is often a challenge to get the center focus point on the moving subject to start with.

By the way in reading the manual I find there are several options for reprogramming the * button. If I understand it correctly you are using option 1 which is AE lock/AF.

Thanks for your suggestions

Jerry
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Old Apr 21, 2006, 12:30 AM   #7
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Hello Jlacasici, you said above:

"...select ashutter speed and f/stop and leave it. This allows the camera to just focus and not have to do any AE processing every time you press the shutter. This is more important on the 20D!"

Is this shooting in AV mode for the 20d or some other mode?


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Old Apr 21, 2006, 9:51 AM   #8
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Personally, I don't use the setting you list. I set it to 4 (at least I think its 4.) It is the setting where AF stops (gives me the equivalent to one-shot) but it keeps doing exposure calculations (AE).

This is because I shoot outdoors almost exclusively and exposure is changing all the time. A cloud could go over the sun, the bird could fly under a tree branch. If you shoot indoors in more controlled lighting situations, then NOT doing AE might speed up the cameras responsiveness (at least I believe that is what Jim is trying to claim.)

I don't know if this is true, but it certainly might be. It will certainly save you battery power, thought. And if you shoot a lot of pictures (at an event or meet, for example) then saving some battery life might be good.

It did take a bit to get used to that setup. But good photography is not easy. Don't expect it to be. Go to a soccer game and practice (in soccer they are always moving.) You will absolutely get better at tracking if you do it more. I know I've gone to the beach with a bag of wonder bread and fed the Gulls so I could practice tracking them in flight.

Using the * key the way I do isn't perfect. I wish it just toggled between one-shot and AI Focus. But it doesn't, and there is nothing I can do about it.. so I just accept it and move on. I'm getting better results with this setup than before. Of course, I'm better too... so is it me, the gear or both? I don't know.

spy,
What Jim is describing is not AV mode. AV mode (also called aperture priority) has the camera assume the aperture is correct (because the user set it) and it picks the proper shutter speed to get the right exposure. If you set this to the largest aperture your lens supports, then you will get the fastest shutter speed (good for stopping action.) What Jim describes is using the camera where the exposure is fixed, and just having it auto-focus. You could do this by switching to manual mode and setting it yourself or you could program the * button to stop doing auto-exposure (AE.)

Eric
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Old Apr 21, 2006, 4:43 PM   #9
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Eric
There are four options for the C4 cutom funtion listed in the 20D manual:
0= AF/AE lock
1= AE lock/AF
2= AF/AF lock, no AE lock
3= AE/AF, no AE lock

Deciphering what these options do from this table is really confusing.

Based on the way you use the * button, which of these selections are you using?

I have tried each of the above settings and am totally confused about what each does/does not do.

Can you (or anyone) please translate these options into English?
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Old Apr 24, 2006, 4:23 PM   #10
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Hi spy,

Sorry to take so long to get back to you, been busy actually shooting :lol:

I have mine set to cf4-1. It didn't take me long to get used to this when I switched, but this is relative as I started using it this year for basketball and I was shooting 1500 images a day. Doesn't take long at that rate to get used to it.

For indoor shots like basketball, I use manual for a setting. I set the shutter and f/stop to get a good exposure based on an 18% card as well as White Balance (even more critical with the lighting in some gyms). When I'm shooting outdoors (baseball, football) I still use the cf4-1,I'm using shutter priority mode (almost never AV) and I will use the shutter pressed 1/2 way down in this mode to get AE readings.

Joe
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