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Old Feb 12, 2005, 1:01 PM   #1
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First of all, let me say that I am new to DSLR, and I am not an expert - probably not even qualified to be called a beginner. However, I really enjoy taking pictures - mostly of my kids. I also enjoy taking pictures at high school basketball games and college gymnastics meets. Therefore, when I decide to purchase a DSLR, I decided to go with Canon 20D so that I would have the 5 fps and 8 MP (for cropping). Initially, I was very disappointed - because I didn't know enough to purchase a good lense to go with the 18-55 kit. So, I quickly began to do some research and decided the 85/1.8 was the best in quality/price for me. I really like the lens - although zoom would be nice. However, I am experiencing a phenomenon that I really dont understand - if I take 2-8 consecutive action shots the odd # photos have one "brightness" and the even #'s take on an entirely different "brightness". I am sure my terms are not correct, but maybe it's close enough. I am curious to know if anyone else has experienced this or if anyone has an explanation of what may be happening.

For illustration, the attachment is an overlay of 4 consecutive shots.
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Old Feb 12, 2005, 3:12 PM   #2
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What are you using for flash? Most of what I've seen with different exposures on my 20D while taking rapid shots is flash related.

With a 580ex you should be able to get around 11-12 shots in a row with flash.

Some canon external flashes will fire even when not fully charged, so the flash exposure might not be as bright.

If you're using the internal flash of the 20D don't expect it to fire with each shot.
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Old Feb 12, 2005, 3:16 PM   #3
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Actually, I am not using a flash. I am usually shooting ISO 1600; 1/500; f/~2 - 2.5.
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Old Feb 12, 2005, 4:08 PM   #4
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Those look like white balance differences to me. If you are using auto white balance, maybe the slight differences in framing are enough for the camera to handle the WB differently.

Still, It doesn't seem to me that you should be experiencing this behavior. I use the DRebel and shoot RAW so WB is never an issue with me. I made an exception a few days ago and shot jpeg. The WB was awful but consistent nevertheless.

Try doing a custom white balance or using one of the presets. Check the manual or someonewho ownsa 20D may post some advice on that.

Another alternative is to shoot RAW but that means time spent onpost-processing and maybe anew software purchase. I don't know anything about the bundled RAW software for the 20D but I do know that lousy software makes shooting RAW a real ordeal - or should I say a raw deal. ;-)

David

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Old Feb 12, 2005, 5:44 PM   #5
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Thanks for the suggestions. I will try to play around with WB - I don't have a clue where it is set now, but I will check it out. Thanks again.
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Old Feb 12, 2005, 6:28 PM   #6
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You could be experiencing that the camera is catching the gym lighting between pulses and reigniting causing different light intensities, noticed by the camera but not to our eyes (60 cycle flicker is not perceived by our eyes but the camera can catch the action much faster).
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Old Feb 13, 2005, 12:20 AM   #7
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It does look like white balance is changing, by default if you did not change it the 20d is set to do auto-white balance when you first power it on. Either preset the white balance and hope or use RAW and work out the right color balance later.

View the movie clips on Kalypso's post http://www.stevesforums.com/forums/v...mp;forum_id=31 I think it is the 2nd one that has some good pointers on color balancing image groups.

Peter.


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Old Feb 13, 2005, 5:23 AM   #8
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What you have are different exposures between pictures... auto white balance somehow depend on that but this is not the problem.
If you want to take pictures of the same zone (5fps or not) you should use "AE lock". If you are in "One shot" or "AI focus" this is done automatically I think... but in your case I am more than sure that you selected AI servo.
Anyway, to be sure select the "AE lock" by yourself. Point your camera to the desired zone, half press the shutter, and press the "AE lock" button (marked "*" on the top-right of the camera. Looking in the viewfinder you will see the "*" mark lit. This will lock the exposure and any subsequent shots will use it. If you are shooting at 5fps you must press-still that button until you are done.
To deselect it wait a few seconds or if you are in a hurry press a button on the back than go back to shooting mode.
I personally use the button next to it (the AF pint selection), then half press the shutter to continue shooting.

But, be warned... there are three problems regarding AE lock...
One: You must reselect it or unlock it in order to get a AE of a different zone...
Two: If you don't get a proper exposure in the first place all your 5fps locked shots can be ruined.
Three: We tend to forget the first problem :-)
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Old Feb 13, 2005, 6:58 AM   #9
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My understanding is these kind of gym light "cycle" and during the cycle they change color temp. Now don't quote me here but I think i remember reading 60 times a second (which makes sense). At that rate the human eye doesn't notice it but your camera does...
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Old Feb 13, 2005, 8:26 AM   #10
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Thanks for all of the suggestions. I will definitely try to take your advice to correct the problem. Also, I must say that I just stumbled across this web site yesterday, and I am very impressed! First of all, everyone seems to be so nice - no one has dismissed my problem as being one of a beginner that doesn't have a clue what he's doing. Also, the wealth of knowledge on this subject (and others that I have reviewed) has been overwhelming. Certainly, a great deal of it is too technical for me (at this point), but I am learning from these posts. Now that I have found a place where knowledgeable, friendly people are willing to share thoughts, ideas,and experiences I will certainly be returning. Thanks again for all of the suggestions.
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