Novoflex makes the EOS-RETRO lens reversal adapter that, unlike other adapters, has a second ring that is attached to the EF mount side of the reversed lens, and electrically connects it to the body's EF mount. Thus, it maintains full controlability of the reversed lens.
This is a slick solution for macro photography. However, at 300 EURO ($540 here), this is also an extremely expensive one.
Is there a cheaper alternative to this kind of device?
Note that I am aware of the multiple Macro solutions. I am interested in this specific configuration.
UPDATE: also, I wonder, will the AF work correctly, or reversed? With phase detect AF the camera knows if you are shorter or longer than the exact focus and activates the AF motors accordingly. But here, the lens is reversed, so the feedback loop is actually a positive feedback. Am I right?