Heya,
I have tried two extension tube kits. First, was a $14 non-electric kit. Worked ok. But doing the whole manual deal with a lens for the aperture takes serious tinkering and I was losing patience and it was really bad for field work for me. So I paid a little more finally and got a $50 electric kitted extension tube for my T4i. I picked up the Fotodiox Pro
for $50 shipped. I read the reviews and some people seemed to have issues, but I figured I could return it. Well, it fits my lenses just fine, and the circuitry works fine. My only gripe was that it took a little working in, to get the mechanisms to loosen up a touch. But after the initial break in of turning and touching, etc, it's smooth and works fine now. Lets me control aperture with camera and all that which is the point, and very important. Obviously with macro you want to manual focus though still.
I hooked up my junk 18-55mm EF-S kit lens to it for fun. I get about 1~2" inches from the subject depending on my zoom, which I tend to leave it around 35mm on the lens, and then just step up or down my aperture depending on the DOF I'm trying to get on my target.
I do both field shots and indoor shots with it of insects and stuff. I do not use a flash. I just use natural sun light. Or I use constant lights near my subject when indoors (I collect things out from under spider webs and off the road, so they don't move... ever...).
Again, done with a 18-55mm EF-S kit lens that came with my T4i, and a $50 Fotodiox Pro circuit extension tube kit. No flash.



Very best,