OOPs, I gave a wrong name! It shoud have been Science Lab Software http://www.optics-lab.com/demo.htm is the address for the download. You can slap my wrist if you find me at RTMC. I'm sorry. I might also mention that somebody needs to do a review of all the optics software out there that's free or near free for doing optics design. Can you at least write up your thoughts on the matter and give it to one of the sites that are doing reviews of amateur astronomy equipment? There's quite a few pieces out there and I helped write one for doing corrector newts that got started by Paul Lind and got put to VB by me and is available at http://www.stargazers-pub.net/ . You might also pick up the program that Stevick did for his Stevick-Paul designs and there's a program out there through Stevick for doing off-axis scopes (they're only a very little more difficult to build than a Newt.).