Edit: yep, I got it, so no need to reply... Hello all! Just bought an used Nikon PK-13 tube + tomorrow will be buying an used PN-11 to be used instead of wobbly Kenko set. I was cathering some info from the net how to use Nikon tubes with a D200. So, did I understand right that: 1) I choose the aperature by aperature ring and the cam recognizes this and no need to use the dial to match the chosen aperature? 2) I have to tell the cam the focal lenght and max aperature of the used lens? Any info will be highly appreciated!