Originally posted by SpecialK If your subjects are not moving, like a building or landscape, then manually focusing is not so bad. However, once your subject starts moving, catching the proper focus becomes more difficult.
Many people on this forum only have manual lenses.
I disagree SpecialK. I do the vast majority of my hummingbird and waterfowl shots with a manual focus Vivitar 135 2.8. I find it easier because I can focus the lens faster than my camera does. The autofocus lenses I have are in my signature and they are good lenses...but...I have not had good luck with Pentax's ability to focus on fast moving objects. As such, I've pretty much moved exclusively to manual lenses. Yes, I can use all of my lenses in manual mode (and do at times), but I find the pure manual focus lenses easier to focus.
If you get manual lenses, start out with a cheap lens off ebay or this forum. You can usually pick up 135mm lenses for very cheap ($10-20 plus shipping). I'd suggest starting with that to figure out if you like that over auto focus because it is personal preference.
After you get it, you'll need a couple weeks to mess around with the functionality. Start slow, use a tripod for things that don't move, and work your way up. While I find I get better results from manual focus, I've seen many people who get really good results from auto-focus lenses. You need to find out which works best for you and your camera.
If you are shooting moving objects, start off with positioning your shot. If you are shooting something that will pass a specific spot (like a race car), focus on that one spot with the right ISO and aperture and wait for the shot. After you've practiced for some time, you'll learn how to track and focus manually at the same time.