Custom Astro Tripod

(click Images to enlarge)

Redesigning and building a better tripod for astrophotography took over 8 months of experimenting. My final design addresses two goals. First to maximize stability. Second to accomodate a range of optical setups.

My scope's original aluminum legs weren't stable enough. By building the tripod legs out of wood, there is better resistance to vibration. Additionally, large triangular shapes give stability.

(For a more complete discussion of tripod design, see “Astrophotography for the Amateur” by Michael Covington (Cambridge University Press, 1985 – 1991))

The legs were made with 1"x2" (actually 3/4 x 1-1/2) oak strips. Rather than steam bending the wood, I used clamping bolts to get the best shape. Notice the spreaders 2/3 up each leg. They provide stability and force the legs to make good surface contact with the mount head.

The problem was how to make fine adjustments to each leg's length. My solution was a cam-design. The attached close-up gives a better view of the design. Each leg has a 1-1/2 inch range of adjustment. Wing nuts are provided for each cam. The edge of each cam is covered with 3M anti-slip stair covering.

Click here for cam template

The bolts just above each leg-cam serve two purposes. First, they hold the horizontal spreaders. Second, they force the leg pieces to meet the cams with good surface contact.

The scope mounting saddle has two unique features. First, the holder is 24 inches long. It is designed for holding scopes with the Vixen-style 1-3/4 brackets. Clamping bolts are placed about every 3 inches. The next feature is the addition of free weights at each end of the mounting saddle. Their purpose is to utilize MOI (moment of inertia) to further reduce unwanted head vibrations. I'll be experimenting with this feature as soon as weather in Wisconsin becomes more astro-friendly.

Here's one of the setups I use. It's for my DSLR. Notice the separate Telrad finder holder. Other setups are for a 80mm APO spotting scope. My main scope is a Astro-Tech 6" f/9 Ritchey-Chrétien. In all cases, the optics are moved back and forth on the 24-inch mounting saddle to attain balance. The weights stay in one position to achieve MOI benefits.
I Hope this gives you some helpful ideas.

Your comments and questions are welcome. Happy viewing.                                         

Harvey Sherman
Hubertus, Wisconsin
April 2011