Close-ups, Filter and Macro Photography

I have found out one thing. Shooting moving objects with the 500D filter on the front of my zoom lens is not easy. I have yet to get an image I like using the filter. The biggest problem I have is I don't use a tripod. It's way to difficult to carry a tripod around in the field and setup for a shot of bug that probably won't be in position when I finish setting up. So I handhold all my shots. Since the 500D sets focus along a thin plane at about 19.5 inches, if I move out or in from the subject, the camera can't compensate outside of that thin plane. With practice I could probably learn ways to do it, but nothing I have tried so far has helped.

I really wanted the filter for close-up photography. As anyone who has looked at my photostream can tell, I do like getting close to bugs. I thought this lens/filter combination would be the answer to my desire to get closer. I guess I'll have to continue searching for that answer.

I know there are macro lens which allow for close up photography, but whether they work with good enough depth-of-field for my purposes or not, I am not sure. I should ask the question on one of the many sites of the internet which might know the answer, but I have found, that in most instances, the answers you get are not what you need. Either the questioner asks the question incorrectly, or readers misread the question, and when that happens, the question isn't answered and the questioner is left wondering just what the correct answer is.

Maybe I'll ask the question and hope for the best. 8v)

If there is a knowledgeable Canon equipment reader reading this entry, I'll ask the question here. You can send me your answer through this site. And now for the question.

When used at its closest focusing distance, how deep is the depth-of-field of the 100mm 2.8 EF Macro? Does autofocus work as I move in and out? Those are the most important questions I have. I probably need to know more, but those are the problems I have encountered with my current close-up combination.