Hello all For a nice visual method, download a copy of NEWT and input your specs for the scope, the program will allow you to tweak the design to avoid vignetting at the tube and focuser. http://www.dalekeller.net/atm/newtonians/newtsoft/newtsoft.htm James Crombie http://www.jamescrombie.com _______________________________________________ ATM mailing list http://www.atmlist.net/