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Canon 20D Focus options
Hello All,
I recently upgraded from a Canon 300D to a 20D and now have some options available that I didn't have on the DRebel. One is the option of choosing between three focus modes. One Shot AF, AI Focus AF and AI Servo AF. I have read the manual until my eyes glazed over, trying to determine which of these modes best suited my application. I use this camera for wildlife photography only and shoot everything in AV mode. I use the center focus point for AF on a still subject, such as a perched bird. If I want to photo a bird in flight for instance, I change to automatic selection (all focus points). I am wondering if one of the 3 AF options would be best suited for both situations or do I need to be changing the AF mode as well as the focus point? I am just not clear on the functionality of each of the three AF choices. I am hoping someone in this group will have experience with them and could offer some advice. -- Bob "Nature Photography by Bob Moul" http://www.pbase.com/rcm1840 |
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#3
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The AI Focus is a mode between One Shot and Ai Servo. Daniel |
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The AI Focus is a mode between One Shot and Ai Servo. Daniel |
#6
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Generally they recommend One Shot for stationary
subjects and AI for moving subjects since AI will track something and hold focus while OS locks to one focus point and stops focussing. Dunno what AI Focus does, sorry ... I found this description of AI Focus on the net ... "There is the usual One Shot as well as AI Servo tracking with predictive autofocus. ... In addition there is AI Focus mode which locks focus in Single Shot mode but then automatically switches to AI Servo with tracking if the subject starts moving while the shutter release is partially depressed." This sounds like a very useful mode to me (all I have is the technologically deprived 1D Mark II and the ancient 1Ds so I don't have this mode |
#7
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Generally they recommend One Shot for stationary
subjects and AI for moving subjects since AI will track something and hold focus while OS locks to one focus point and stops focussing. Dunno what AI Focus does, sorry ... I found this description of AI Focus on the net ... "There is the usual One Shot as well as AI Servo tracking with predictive autofocus. ... In addition there is AI Focus mode which locks focus in Single Shot mode but then automatically switches to AI Servo with tracking if the subject starts moving while the shutter release is partially depressed." This sounds like a very useful mode to me (all I have is the technologically deprived 1D Mark II and the ancient 1Ds so I don't have this mode |
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Bill Hilton wrote:
Generally they recommend One Shot for stationary subjects and AI for moving subjects since AI will track something and hold focus while OS locks to one focus point and stops focussing. Dunno what AI Focus does, sorry ... I found this description of AI Focus on the net ... "There is the usual One Shot as well as AI Servo tracking with predictive autofocus. ... In addition there is AI Focus mode which locks focus in Single Shot mode but then automatically switches to AI Servo with tracking if the subject starts moving while the shutter release is partially depressed." This sounds like a very useful mode to me (all I have is the technologically deprived 1D Mark II and the ancient 1Ds so I don't have this mode Bill, On the 10D and D60 cameras, I never found the AI, or AI focus were of much good for fast subjects, especially when unpredictable, like birds at takeoff or landing. On the IDII, I've set the AI to maximum rate and then it does real well (but my dogs playing are still faster). Back to the 10D and D60: for fast action, I learned to use single shot, and to lift my finger off the shutter and then press it completely again. I got a higher number of in focus shots. With AI or AI focus, I got a lot of slightly out of focus images as the cameras always lagged behind. Example, my Great Egret in Flight 1 image, at http://www.clarkvision.com/features/...004/index.html was done on a D60 in single shot mode. So, I wonder if the 20D is more like the 10D or 1DII in its AI tracking ability. So to Bob, if you find the birds out of focus with AI, try single shot. Just remember to lift your finger completely off the shutter button between shots. I could frame at almost 3 per second with this method once I learned it. Also, use only one sensor as with multiple sensors, the camera can get confused and focus on the wrong thing from what you want. Roger |
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Bill Hilton wrote:
Generally they recommend One Shot for stationary subjects and AI for moving subjects since AI will track something and hold focus while OS locks to one focus point and stops focussing. Dunno what AI Focus does, sorry ... I found this description of AI Focus on the net ... "There is the usual One Shot as well as AI Servo tracking with predictive autofocus. ... In addition there is AI Focus mode which locks focus in Single Shot mode but then automatically switches to AI Servo with tracking if the subject starts moving while the shutter release is partially depressed." This sounds like a very useful mode to me (all I have is the technologically deprived 1D Mark II and the ancient 1Ds so I don't have this mode Bill, On the 10D and D60 cameras, I never found the AI, or AI focus were of much good for fast subjects, especially when unpredictable, like birds at takeoff or landing. On the IDII, I've set the AI to maximum rate and then it does real well (but my dogs playing are still faster). Back to the 10D and D60: for fast action, I learned to use single shot, and to lift my finger off the shutter and then press it completely again. I got a higher number of in focus shots. With AI or AI focus, I got a lot of slightly out of focus images as the cameras always lagged behind. Example, my Great Egret in Flight 1 image, at http://www.clarkvision.com/features/...004/index.html was done on a D60 in single shot mode. So, I wonder if the 20D is more like the 10D or 1DII in its AI tracking ability. So to Bob, if you find the birds out of focus with AI, try single shot. Just remember to lift your finger completely off the shutter button between shots. I could frame at almost 3 per second with this method once I learned it. Also, use only one sensor as with multiple sensors, the camera can get confused and focus on the wrong thing from what you want. Roger |
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Bill, this is the mode I have been practicing with after reading the text in
the manual. I have not had much of an opportunity to try it on birds in flight because of the weather, but I have tried focusing on objects like a tree trunk, than while half depressing the shutter release, move the camera to another object at a greater or lesser distance and the focus almost instantly locks onto the latter. That is while using the center focus spot. I agree with you, this seems to be the most versatile mode. -- Bob "Nature Photography by Bob Moul" http://www.pbase.com/rcm1840 "Bill Hilton" wrote in message ... Generally they recommend One Shot for stationary subjects and AI for moving subjects since AI will track something and hold focus while OS locks to one focus point and stops focussing. Dunno what AI Focus does, sorry ... I found this description of AI Focus on the net ... "There is the usual One Shot as well as AI Servo tracking with predictive autofocus. ... In addition there is AI Focus mode which locks focus in Single Shot mode but then automatically switches to AI Servo with tracking if the subject starts moving while the shutter release is partially depressed." This sounds like a very useful mode to me (all I have is the technologically deprived 1D Mark II and the ancient 1Ds so I don't have this mode |
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