Telescopes that didn't work as well as I hoped
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13.1-inch String scope, f/4.4 Newtonian, with spring counterweight
13.1-inch String scope, f/4.4 Newtonian, with spring counterweight
The primary problem with this scope is that it was much too top-heavy, and although the spring counterweight worked, the center of gravity of the entire scope was so high that the scope would lift off the ground when pulled below about 40 degree altitude - yikes!
The altitude and azimuth motions were too stiff as well, but it wasn't worth the effort to fix because of the balance problem - and is why this scope will be re-built.
String scope made of Alucobond and fold-able tent poles, designed to break down and fit into its rocker box for airline travel. Alucobond is a material made for cladding the outside of buildings and is two very thin layers of aluminum bonded to a central layer of engineering plastic. Great stuff to work with but it's more expensive than plywood. It's big pluses for telescope making is that its impervious to the elements and is very flat and stiff material.
The scope also uses a spring counterweight to counteract the low center of gravity.
Completed in May 2007, just in time to go to Hawaii. The assembled scope weighs 36 pounds, but as light as that is for a 13 inch scope, it's still a lot of weight to lug through airports. Next time I'll find a piece of luggage with wheels that it will fit into.
Hey, it works - sort of. A week after completion it's relaxing by the pool on the Big Island of Hawaii - its one and only trip. The light baffle has been added opposite the focuser.
8-inch f/3.3 travelscope
8-inch f/3.3 travelscope
The main problem with this scope was that I could never get the altitude and azimuth motions as smooth as they should be. The one arm altitude design was the root cause - it put a great deal of torque on the altitude bearings, as well as the entire altitude arm, which in turn flexed the already reinforced rocker base.
This translated into annoyingly stiff motions in both axis, greatly reducing enjoyment of the wide field views.
I tried adding ball bearings, and although that helped, the long term flexing of the rocker base torquing the altitude bearings convinced me this wasn't a design worth pursing any longer.
This scope has been successfully rebuilt, and can be seen in the Other Telescopes page.
Note the Rigel Systems finder mounter on the mirror casing (a real-life cake tin). This proved impossible to use and was quickly moved to the top of the tube. That wasn't much better and was subsequently replaced by an experimental right angle, correct image reflex finder which works quite well.
I should also note that the black upper part of the tube was rather shaky, which added another layer of annoyance when observing. A short focus 8-inch scope should be rock solid.
The shelves were handy for storing things like an eyepiece, glasses or the diagonal cover during observing, but their primary purpose was to reinforce the altitude arm.
This scope made two trips - one to the Big Island of Hawaii (mostly successful) and one to Maui (clouded out). Minus the table the scope is sitting on the photos, the entire scope broke down and fit in a large, but normal suitcase. I carried the optics in a separate bag as carry-on baggage.
8-inch f/4 on a Modified English Yoke mount
8-inch f/4 on a Modified English Yoke mount
My first home made telescope was this 8 inch f/4 Newtonian on a Modified English Yoke mount. It was made out of scrap 2x4's and was huge. To give the below photos some scale, the north-south dimension of the base is about 7 feet long.
I copied the design from a photo on page 34 of The Amateur Astronomer's Handbook by James Muirden, partially because it looked like a real telescope and partially because the caption said it was made entirely from wood. I had wood! The year is 1969 and I was 14.
It didn't track even though I tried to install the RA drive off the 3 inch Tasco GEM - the huge wooden mount was way too much for it. Once I took the drive off the mount it did move pretty smoothly by hand, though it was a pain to rotate the tube in its cradle to place the eyepiece in a comfortable position. Sometimes there wasn't a comfortable position.
So I was happy to put the telescope on a nice German Equatorial Mount in 1974. That's when I began regularly writing notes and making sketches simply because the GEM made observing so much more comfortable.
And finally, I'm so very happy to have these three photos at all - I looked for them for years without success, and was thrilled when I finally came across them.
The RA and Dec motions were pretty smooth though, and the settings circles I made for this mount worked well enough to get me in the right area more often than not.
I'd figured out that the polar axis of a telescope mount needed to pointed at the NCP near Polaris, so I only needed to move the mount in RA to keep track of an object, which I thought was pretty awesome.
I still have the 8-inch f/4 mirror and it lives in the Springsonian mount I came up with in the mid-1990's: Telescopes . I refigured the mirror in 1980 and have been happy with it ever since.
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