I bought an Orion 120mm f/8.3 last year and was so impressed with the optics that I decided to buy its big brother the 150mm f/8 Synta OTA. The problem was that it was too long to use on my Universal Astronomics UniStar mount (alti azimuth) and too awkward to use at zenith, so I decided to try a new approach by folding the light path and bring it out the side. This was accomplished using a Newtionian secondary mirror (3.1 in) and mirror holder.
This addresses both objectives, reducing the tube length to 36 inches and by the use of a 2 inch diagonal, keeps the eyepiece comfortably oriented throughout the altitude range from horizontal to vertical. The diagonal is rotated in the focuser as the altitude angle is changed, keeping the eyepiece in the same relative position within the 13 inch arc of rotation.
This allows for easy sweeping of the telescope, which is intended for rich field viewing of the Milky Way starfields and also comet searching.
The "tube" is constructed of 1/2 and 3/4 inch birch cabinet plywood, and the interior is completely lined with 3M flocking paper to maximize contrast.
The focuser is a custom MoonLite refractor focuser similiar to the model used to retrofit the 120 and 150mm Syntas. I had it made completely matte black and a flat base to allow mounting to the tube.The inside of the drawtube is lined with flocking paper to completely eliminate unwanted reflections.
The objective is the standard Synta; I hacksawed off the collar that screws onto the tube, retained the lower part of the cell that allows collimation.
The entire tube assembly complete with AP diagonal and 40mm Konig ep and Telrad finder weighs about 28 pounds.
Mr. Bill
Mounting would be very tricky though, as would alignment.
