I have owned this tube for a few years. It is a great piece for close-up work however I find that it is somewhat extreme. You get really close up, which is great for some subjects but not so good for others.It is so close it's hard to focus on the entire subject sometimes. If you want extreme closeness, go for it. If you what a little more versatility, go with the 12 II version.

This extension tube is great, works exactly as expected. The AF works even with the ef-s lenses ...

If you like close up macro work then this is a necessity. It works great with my two macro lens, Canon EF-S macro and Sigma 150 macro, have also used it with my Canon 135L and 85 f/1.8 and have been very happy with the results. You do lose the ability to focus to infinity so it is primarily for macro work.

This is a very easy piece of equipment to use to make your macro lens get that closer look at your macro subject.

You can focus closer than without it, but you lose the ability to focus all the way to infinity. AF and TTL work just as good as without this between the lens and body. If you are interested in macro work you may want to look at the 60mm or 100mm macro lens before buying this since they allow 1:1 reproduction without any special attachments.