I've read that the manual focus system in the Panasonic 20mm f1.7 is actually driving the motors to focus, and that turning the focus ring at different speeds affects the speed of the focus change. I had this in the lens of my old camera, and I was not a fan of it, because manual focus didn't operate like true manual focus should. For the owners of the pancake lens, is the manual focus annoying, or easy to use? Should I just invest in a 28mm Canon FD and rely on the less expensive MF?