Quote:
Originally Posted by gregbradley
A myth: Having tube rings on this telescope does not distort the wave front, or mechanical orthogonal of the system.
So I take it from your brief review here you would not recommend this scope over a good fast refractor despite the fast speed of the RH200?
Greg.
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Hi Greg, No, I did not say that. I make no such recommendation. F/3 requires a mastery of the beast. You are dealing in collimation and tip tilt adjustments of just a few microns, and systems with this tight tollerance need the mechanical + thermal stability, and fine adjustments to enable success. It could be an f/3 refractor, f/3 compound telescope, or f/3 Newtonian. You also need to make sure that your narrowband filters are optimized for f/3 as well. And as you have read, the steepness of the light cone negatively impacts the use of an OAG.
I solved a few things with the RH200 which is typical of any telescope shakedown for imaging:
- precise and measured adjustments of the tip-tilt backplate
- proper spacing of the CCD camera from the rear optical element
- motorized focuser
- optimized bandpass for narrowband
- Classic tube riings with dovetail support for stability
- Separate guidescope with high sensitivity
- Dew heater tape on the front element
- Solid, precision mount (in my tests, an AP 1200 goto)
There are some clear advantages to the FSQ:
- Larger image circle
- Ability to motorize the rotation of the camera angle
- f/5, better performance with 3nm narrowband filters
- No dependency on critical distance from optics to the CCD array
- No central obstruction
jg