This program calculates off-axis illumination and diagonal shift.
This program analyses newtonian diagonal off-axis illumination and calculates the diagonal offset. Written by Mel Bartels, 2-6-90. Sources are mid-70's Sky and Telescope article on diagonal size and Telescope Making #9, pg. 11 on diagonal offset.(Ported to JavaScript by Rafael Barberá, 13-3-96, for metric units adapted and reset button added by Tomáš Maruška, 5-11-1999). Microsoft's Internet Explorer 3.x has trouble with this JavaScript: hit the reset button between calculations.