These photos show various views of the 4.25 Newtonian reflector telescope I built to serve as a finder scope
for the 17.5 in. Dobsonian I built several years ago.
After a few years of using the big Dob I began to wish it had a larger aperture finder scope on it to help me hunt down fainter objects. I had an 4.25 in. Newtonian telescope that I had built many years before. It was my "Travel Telescope." A small telescope that fit in a small suitcase with my photographic tripod and some eyepieces. I have taken it on vacation trips with me all over the country and sampled the dark skies of many of the places I have gone on my vacations (See my vacation photo page).
I tried mounting this scope as it was on the side of the 17.5 in. Dob, but I didn't like the look of it. The small scope originally had a white plastic tube which just looked out of place stuck on the side of the big, wooden Dob. So I decided to try making a wood tube that would match the wooden Dob a little better.
My original plan was to make the tube out of oak. But before cutting up a lot of expensive fine wood, I wanted to make sure I could really pull it off. So I started with some scrap fir I had laying around the work shop. I cut and joined ten pieces to make polygonal cylinder. Then I turned the outside round on my wood lathe. The result turned out so nice that I decided not to bother redoing it in oak and just went ahead and used the fir prototype. So I slapped a couple of coats of polyurethane on it, painted the inside black and put it all together.
I was able to reuse the primary mirror cell, secondary holder and focuser from the original telescope, and since I used scrap material for the new tube, putting it all together cost me NOTHING at all. I love projects like that!
I also knocked out a cradle that holds the finder scope and mounts on the side of the big Dob with (believe it or not) Velcro. There are a couple of alignment screws on the cradle that allow me to adjust the position of the finder slightly to bring it into alignment with the main scope.
As you can see from the photos, I think I achieved my goal of creating a finder scope that matches the big Dob. The last photo is a long shot showing the two scopes in the early morning light after a long night of great observing at The Saint Petersburg Astronomy Club's Hickory Hill dark sky observing site near Brooksville, FL. In the background is the dome of the Raden Memorial Observatory.
Click on the photos for larger images.
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