I have started to use my SB800 as an auto focus assist in lowlight situations even when I do not want to use flash. It really helps - light can be so low that the camera with the normal focus assist lamp (D70) simply can not find a focus lock - Pop on the flash for the IR focus assist and lock is almost instant.
Question - I have only used so far at distances of 10 feet or less. How far out is the IR beam effective and is it's angle tied in to the focal length of the lens/flash - In other words will it help with the 70-200 at lets say 50 feet @ 105mm or is that just asking to much?
I know I can try it out and find out myself (and will) but I thought someone here might already have some experience doing this.
