Ken

I guess I've noticed the autofocus takes the most time focus if the subject is moving...or if you're trying to shoot thru glass. We use the "prefocus" method if we're setting up for a moving subject. You just hold shutter button down part way on some fixed object that's near where the subject will be when you're ready to shoot. Keep in mind, you'll have to hold the button until it's time to snap the photo. This is OK for a few seconds. Now, if your subject is 100' or more away, then it doesn't make much difference, camera will probably got to infinity focus anyway. I believe most digitals will hold that focus until the next photo.

The second method is to switch to manual focus. Many models of digitals have selector allowing you to choose manual focus. Just make sure you remember (or whoever is camera operator) that you are in manual focus. Then, just twist lens & pre-focus. It'll hold that focus.