I own one, and yes, it's true ... sort of. With a long lens, you have to manually focus somewhere near, then the converter will fine tune the focus for you. It even works in good light and high contrast with my M 400mm f/5.6. Anything less and it just hunts and gives up. As it is stated to work only with lenses f/4 and faster, I cannot complain. There is a thread where I posted my results on a wintry day.
http://www.pentaxforums.com/forums/p...00-af1-7x.html