AF Sensitivity

woodswill

Out of the nine focus points, if I focus with the central focus point, will the image be twice as sharp in focus as compared to the image clicked with the other focus points?
The manual says with all the auto focus points, cross type AF sensitivity to both vertical and horizontal lines is possible up to f/5.6. I am not able to understand what the manual wants to convey here? Does it mean that with an aperture number more than f/5.6, say f/7/f/8,f/10,f/18,f/22,f/32, all the AF points will not be in sharp focus? Does it mean that in such case only the central focus point will be in sharp focus?
Further, the manual says (page 79) that with central AF point the high precision is up to f/2.8? Again, I am not able to understand.
Will you please guide?

tazman

Woodswill that is a very good question. The manual isn't really clear on using and understaning Canon's autofocus system. Check out the following link for a very good and very detailed explanation of how to use Canon autofocus. http://www.youtube.com/user/BHPhotoVideoProAudio/videos?query=Canon+Autofocus

Tazman

woodswill

@ tazman the videos you have referred are highly informative. I've never gone through stuff like this. Mr. Rudy Winston, the man from Canon, has the clarity and deep understanding of the gear, and he knows what he says and what he means. He has explained the meaning and usage of AI Servo in such a beautiful manner that it's impossible to make errors after listening him.
I am still not clear about one thing. Does the central focus point have more sensitivity than the other focus points? Learning from the video, I now believe that all the focus points are cross points in the Canon 60 D and it's important to use these focus points while framing the shot. There may arise a need for recomposing the shot, but if the manual focus points have been carefully selected, there is no need for recomposing the shot.
Does this mean that the sensitivity at the central point and other points is the same? I am not 100% sure.
Perhaps Mr. Moose can clarify the doubts.
Thanks once more dear Tazman for such quality stuff.

maiMelissa

Woodswill - thanks for your question. It's basically the same question I have been meaning to ask. I will have to listen to the videos too and see if I get my answer. The other question I have is do many photographers set their own focus point or do you just use the one the camera automatically sets? If you do use your own how do you determine that it is the right autofocus point? I hope I'm not asking an obvious question!

Auston

@maiMelissa - Some set there own points. I do sometimes when I have a certain image in mind that I am going for. Other than that I usually run with the single middle AF point.