Originally Posted by cj3waker
I have a d3100, and purchased a decent 35mm lens
the lens is af-s and supports autofocus during normal shooting, but I cant seem to get it to autofocus while recording video, and ideas?
I have the D7000. If the 3100 auto focuses anything like it you have to push the center button on the AF/M focus lever. The lever should be in the AF position, not the M position.
Once you push and hold that button you use the main command dial to select AF-F, (full-time af). While holding the center button and using the command dial you should be able to toggle between AF-S, (single servo AF) and AF-F. This should all be in your owners manual.