Backyard Voyager
How to Build a 13" Hemispherical Reflector for around $1,000.00
by Duane Frybarger
Ever since I started observing in 1997, it has been my dream to own a large aperture telescope. The major drawbacks were the cost, size and weight. When I saw a 13.1" Coulter mirror on Astromart that was being sold by my friend Jorge Morales, I realized this was my chance to get my "dream scope". Jorge graciously allowed me to purchase the mirror on an easy payment plan. I had seen an article in the March 2003 Sky and Telescope with instructions on how to build a hemispherical reflector by Randall Wehler and after some research, I started purchasing parts and planning the details. I live in a flat and have no shop to work in, but I have a couple of friends with tools along with the space and skills to use them.
I purchased the mirror in October of 2004 and the scope was completed by Christmas of that year. However, it took another year and a half of tweaking to get everything working to my satisfaction. The finished scope is a pleasure to use - it moves smoothly in any direction with the eyepiece almost always at a comfortable height. Vibrations are minimal and setup and breakdown take only a couple of minutes.
The only disadvantage of this design is the weight of the scope when ready for transport. The mirror bowl, secondary ring, counterweights and base weigh 60 lbs total, which is a bit heavy to move in and out of my back seat.
I have experimented with assembling the mirror bowl each time I observe, however, I am currently transporting the scope with the mirror bowl assembled. Setup and breakdown is about five minutes without assembly of the mirror bowl and about five minutes more with assembly. The advantage to disassembling the mirror bowl is that the counterweight (25 lbs) travels separately and makes the remaining package much easier to move in and out of the car. However, it's a problem finding a safe place for the mirror and "mirror cell" when I'm setting up and breaking down.
For details on how it all went together, step right this way...
If you're going out observing tonight, be sure to visit my Deep Sky Database to build your observing lists.
Questions, comments? Send an email to duanefrybarger@yahoo.com.
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