 Alex B. Smith |
Autofocus points in Av mode? I have a question about how cannon chooses its autofocus points and how they work in conjunction with the shooting mode (I have a 20D). If I left the camera in full auto mode for example, the focusing would pick the farthest and nearest focus point, and choose the correct aperture. The problem with this is that 99% of the time it would require too long of a shutter, so most photographers put it on Av mode at minimum aperture (wide open). In this particular case, in Av priority, why does the camera still try to focus on all those nine points? And even then, they appear to be random. One of my shots focused on the nearby leaves and not on the far away subject. Should I get ride of the diamond nine point focusing and make the only focus the center point? I want to choose my subject, I dont want the camera to do it.
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W. |
Well, you asked and answered that yourself, now, didn't you, Alex? The camera's systems do the best they can, but they're not infallible. As you found out. OTOH, neither are you, of course.
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Rake the leaves?
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
"Well, you asked and answered that yourself, now, didn't you, Alex?" Haven't you've said that to him quite a few times before?
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W. |
I did? Could be. I'm not keeping track. You do? Anyway, if so, that sort of seems to reveal a pattern then, doesn't it?
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
Never mind. I think it was somebody from an Asian country.
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Jon Close |
>>" ... If I left the camera in full auto mode for example, the focusing would pick the farthest and nearest focus point, and choose the correct aperture." << That is only the case in the A-DEP exposure mode, no other mode works that way. >>" ... in Av priority, why does the camera still try to focus on all those nine points? ..." << Because you have the camera set for Auto AF Point Selection (AFPS), pp. 67-68 of the 20D instruction manual. With AFPS and the AF mode set to One Shot or AI Focus, the camera tends to choose focus on the nearest subject it can identify. With AFPS combined with AI Servo, it will start AF at the center sensor, but move to the other sensors if it thinks the subject has moved off-center. (pp. 65-66) In Av, Tv, and P modes you can also manually select a single AF point to use.
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Jon Close |
"In Av, Tv, and P modes you can also manually select a single AF point to use." Oops, I forgot you can also make that selection in M mode.
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