Posts Made By: VishnuReddy GreggParis

Aha! There you are! Looks very nice, Scott. Hope to come out soon and see it in person.
Gregg

The program NEWT.EXE or NEWT2.EXE will lay out any Newtonian optical assembly. In place of a standard elliptical flat at 45*, a near round mirror at some other angle (even one at square on for a three-mirror) is used to push the focal point back down the tube's length.

The field derotator has several situations you should be aware of:
The barrel passing light through it restricts the true field of view, more than without it, of course.
The increased seperation of a camera from the scope, after you add in the filter wheel, any off-axis guider assembly, and then the derotator, will make the magnifications different from what you expect. That is because of the motion of the main mirror to create enough back focal distance to contain all those extra distances.
The derotator has a drive gear like all motion control devices, and this is subject to adjustment problems like backlash, non-uniform motion, missed steps, and variations due to the position of the scope when pointed at areas in the sky. These variations could be within the mount (non-perpendicular axes) or external (atmospheric refraction, not accurately aligned with computer's sky).
An alt-azimuth drive cannot be used for imaging at the zenith, where the cleanest and most stable air might be. This is true whether or not a derotator is used.
The equatorial mode of the Meade 16 fork, depending upon the degree of tilt, is subject to greater vibrations than the alt-azimuth, and must be balanced more carefully. An equatorial pier for the 16" should be investigated. A wedge that is adjustable for that size scope must be carefully made. I have made a wedge for an old style 12" LX200 and made other equatorial mounts, and found them not easily used.