another one from POTN, which brings me to a question. How legit are extension tubes? I think I have the basics of how they work. by extending the distance of the lens from the mirror, it allows the lens to focus closer than it's set minimum focusing distance? I did a quick google search, and found a bunch of "3 piece sets" that you can stack, or mix/match different lengths to get your desired shot. Do brands really make a difference on something like this? since all they're doing is acting as an extension, would the "ebay" ones get the job done? I've got almost an identical camera/lens setup to him, and would love to be able to take shots like these, without forking over the dough for an expensive macro lens.