Can anyone provide some insight into what the best options are for extension tubes? For a beginner photographer, I don't have a fancy setup or a macro lens. That being said, i'd like to take some macro photos this summer. In doing some small research on extension tubes it looks like there's a ton of options. My question: - is it really worth spending $150+ for a Canon-specific extension tube or can a person cheap out and buy a $5 to $8 special on ebay? I've heard the only difference is AF and non-MF with the cheap one, plus some lost quality but not a great deal of difference. Insight would be great. Thanks!