My Page


My pride and joy - the Unitron 4 inch f/15 Model 166 equatorial refractor.

Originally this instrument was a circa 1960s Unitron model 152, 4 inch equatorial owned by John Calabrisi who was formerly a Planetarium Director for the Pittsylvania County Schools Planetarium in Chatam, Va., and Assistant Director at the Roberson Museum Planetarium at Binghamton, NY. Mr. Calabrisi donated the Unitron to the Kopernik Astronomical Society also of Binghamton, NY in 1974. Although the instrument was initially used often, over time it fell into disuse with many parts (including the objective) eventually turning up missing. Some years back, as the telescope was about to be junked, one of the pernik members George Normandin saw an ad placed by me when I was looking for a Unitron "super-focuser". Mr. Normandin responded to the ad and asked if me if I would be interested in the entire telescope. In Mr. Normandin's words "It took some work [....], but the pile of junk went to Len." For a look at many photos that I took of this telescope from the very first time I received it, all the way to it's finished stages, click here to see the slide show which I published on YouTube:


The telescope is now fully restored and has been converted to a model 166, 4 inch photo equatorial with fixed pier. The pier is  the product of  the wonderful hands and talent of James Witt of Phoenix, Arizona who built the pier as an exact replica based on photographs of originals.

Posted here is a selection of images of the restored Unitron 166. Click on the image to see a larger size.


I needed a Unibalance assembly too. Well that was next to impossible to obtain. So after much searching on the Yahoo Groups, I found someone in the Unitron Telescopes Group that was nice enough to give me all the exact measurements of the Unibalance weight, and rod.  I went right to work!  After doing much "Google-ing" around the web I found some end user/suppliers of small stock metals. So I purchased some SAE-1010 carbon steel bar round and Type-304 stainless steel rod to make this assembly.   See the photo below:

Sometime in 2007, I managed to get the weight drive for my Unitron.


Now this is a real showpiece.  The brass governor spins as weights, held onto a cable pull the cable off the drive wheel by means of gravity. This in turn moves a series of gears inside this unit. The speed is regulated by means of the weights on the governor. It is simply wonderful to watch this work.

Well, when I got this unit, there were parts missing too!  For instance, I needed more weights. I didn't have the whole set. So back to the website to buy some 4 inch bar round carbon steel again. The company I bought the steel from, cut it to just the sizes I needed.  A friend of mine that runs his own machine shop gladly drilled the holes and made the slots so I could slide the weights onto the cable and beveled the edges for me too. All I needed to do there was paint them with a black wrinkle finish.

The metal tray was in horrid condition. I sanded the surface smooth and painted that with Rust Oleum primer and over coated it with Black Satin Finish. Another very good friend of mine, made the brackets for me that are attached to the tripod.  These parts are all replicas of the original missing parts.  Thank goodness for the friends on and the Unitron Group on Yahoo Groups. They helped by giving us the necessary pieces of information to build these parts.

Here are some more shots of the various parts and various angles of this beautiful telescope.



No, I do NOT use those crazy sun filters. But I do use the one on the right only when I use the Herschel Wedge. I have a Unitron Herschel Wedge too.  I got it all Unitron!!

Now here is a shot of the Moon I took with the Unitron!

Copyright 2018 Len Marek's Astronomy Webpage. All rights reserved.
Last Updated
November 6, 2018