Difference between spot and single-point AF

[Brendan7]

Hi all,


Does anybody know (on the 7D) the difference between spot/singlept autofocus mode? What are their differences, and which is faster?


Can some people please shed some light on this for me [8-|]


brendan

[Brendan7]

Daniel? Where art thou?

[Wes]

Single point just uses one of the focus point and then spot uses a smaller portion of that single point. So if you are using the center focus point when you use spot focus you are just using a small part of that focus point. Say you want to focus on someones eye with single point focus you may actually get focus on the eye lash but with spot focus it reduces the focus are so that you only pick up the eye ball itself to focus on thus giving a more precises focus.

[Brendan7]

thanks Wes, good to know. I'm using single-pt from now on...


[]

[scalesusa]

The center focus point is in the shape of a cross, and actually contains many photosites in a vertical and a horizontal strip. The sensor size is actually larger than the red rectangle you see in the viewfinder.


Switching to spot on the 7d merely turns off some ofthe photo sensors on the extreme left, right, top and bottom such that the area is smaller.


Canon has information about spot AF on page 10 and 11 here. http://www.canonrumors.com/files/1dm4cfnguide.pdf


Even though it discusses the 1d MK IV, most of it applies to the 7D except the part about requiring super telephoto lenses.