Any difference in accuracy of Canon Focus between Spot and Single Point?

[Doug Schurman]

Most of the time I have my focus set to Spot (the smaller point focus) on my 7D. I'm wondering if one mode is known to focus any more accurately over the other?

Thanks

[arash_hazeghi]

It does not make it more accurate necessarily but it makes the AF sensor sample a smaller area within the AF frame. Here is a case where I find it useful:

You have a bird that is partially blocked by some weeds in the foreground and want to focus on the eye. If you use the normal AF frame and one of the weeds falls into that frame, AF will most likely grab the weed in front of the subject because it is closer, now if you select spot AF, it will grab the eye.

hope this helps

[Doug Schurman]

Thanks for the response Arash. I certainly understand why you use the spot AF. In fact my camera is set on spot for >95% of the time so that there is less chance I focus on the wrong thing.

I was really wondering if by focusing by using a smaller sample area made it less accurate then the large square.

Thanks
Doug