A couple Mark III AF Area Selection questions

[Hillside_Shep]

I just got my Mark III and I was reading the manual to set my camera up.

1. I don't understand the difference between Single-point SPOT AF and Single-point AF. Can someone please explain when I would choose one over the other?

2. My main use for this camera now is shooting photos of my twin 2 year olds. Can you suggest an ideal AF Area Selection Mode? AF Point Expansion? Also, what AF Mode do you recommend?

Thanks. Sorry if I posted this in the wrong area. If so, please let me know for next time.

 

[swampler]

AF spot is just a smaller spot than the single point.

 

[zim]

Have you checked this resource out?

http://learn.usa.canon.com/resources/articles/2011/1dx_af_pts_article.htmlp

 

[Mt Spokane Photography]

You might chose spot AF if you are shooting thru a small opening in a fence or obstruction and do not want to focus on the closer object. The drawback is that you must keep the tiny spot right on the money, or AF will be off. Using the surrounding points for moving subjects allows the center point to drift off slightly and the helper points to keep autofocus without it focusing elsewhere. Its like having a larger center point. That can be good for running or moving sports figures.

Here is a case where I used spot focus just to see how well it worked with my 5D MK III. It works very well, as it does on my 7D. This is a 1:1 crop, so the tree twigs can easily capture the autofocus.