I read this morning in the May issue of Popular Photography that Kenko is bringing out new sets of tubes--the usual set of three, in 12, 20, and 36 mm. lengths. These will supposedly support Pentax AF.
They will cost--$219 U.S. I don't know if that's MSRP or street price. So far they are not on the THK web site. But watch for this if interested.
Joe