There is a 20 x 1.625 18 point design at http://pong.telerama.com/~mdholm/atm/cells/index.html It has good deformation numbers, so we can assume that the one optimized for your focal length will be only a little different, and will be good. Mark Holm mdholm@telerama.com _______________________________________________ ATM mailing list http://www.atmlist.net/