8" F/3.9 RFT - my first mirror

Well, this was a challenge.  My first mirror was sitting a box in the closet, fine ground to about F/4.  It needed to get finished.  So, I rebuilt my focault tester into a slitless model, fine ground, polished, and figured it with a subdiameter lap.  It took about 3 months and I learned many valuable things.

The scope tube is 10" sonotube, painted Rust-Oleum Royal Blue.  The inside was sanded until the paper was rough, and then I just poured in some primer and rotated the tube.  It was then spray painted flat black.  This made a nice bumpy black interior, as you can see in one of the pictures below.  I made a three-vane offset spider, which works okay.  The focuser is a JMI NFG-3 (with fine focus).  The wood is 3/4" Poplar plywood.  The tube box is hinged and opens when the cam lever is released, allowing the tube to be removed or to be rebalanced.

8in F/3.9 side 8in F/3.9 View in tube Mirror cell

The mirror cell is a simple three point cell with Teflon pads.  Three wooden knobs pull the three corners of the cell against springs, and allow nice control of the motion.  I can reach the knobs while looking in the focuser.

This scope usually sits on a heavy-duty wooden tripod that I built, somewhat based on Berry's refractor tripod from "Build Your Own Telescope".

This scope not only shows beautiful star fields in the milky way, but also sharp, contrasty views of planets.  It provided good views of Mars during the 2003 opposition.

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