Coulter Odyssey Compact 10.1" f/4.5 Dobsonian

5.0 Coulter

Low cost, good quality optics and aperture, aperture, aperture!

Lots of weight and the need to repeatedly handle the objective mirror in earlier models.

I bought my Odyssey Compact 10.1-inch Dobsonian telescope new from the manufacturer for $299.95 in early 1986. I had been using a 15-year-old department store refractor and had caught a case of Aperture Fever from too many years of looking at the Deep-Sky photos in Astronomy magazine. Hand-made and in high demand at the time, I had to wait 4 months until the scope was delivered.

This scope, although the smallest of Coulter's "Classic" Dobsonians, is still heavy and BIG. Fully assembled, the un-accessorized scope weighs close to 75 pounds. I don't recommend a mid-size or larger Dobbie for anyone who's in less-than-decent physical shape or doesn't own some form of handcart.

The scope came stripped-down, the only accessory being a 27mm Kellner eyepiece that fits into a very basic 1.25” rack and pinion focuser. There is no finder. The 2.6-inch elliptical diagonal is mounted on a heavy steel bracket. A multi-page manual details how to use the scope and how to maintain it as well as instructions on how to make a 3 ½ inch diameter off-axis stop-down mask to turn the scope into a 90mm, f/13 unobstructed reflector.

Construction is very simple as is usual with Classic Dobsonians. The 13.5-inch diameter Sonotube is mounted into a large flake board box with a trap door at the back for the insertion of the 10.1-inch f/4.5 objective mirror. The mirror is inserted before use and removed for storage and transport. (I never got used to having to repeatedly handle the 8-pound slab of Pyrex glass. Later versions of the Odyssey line of scopes had “real” mirror cells that eliminated the need to constantly remove the mirror. The box at the back of the tube was also eliminated, reducing the scope's total weight.) The mirror’s “cell” is a simple sling design with the 1¼-inch thick mirror resting on three 10-24 screws which can be adjusted for easy collimation. The tube assembly then rests on the scope’s rocker box. The scope’s maximum height of 51 inches puts the eyepiece in the perfect position to observe while sitting down (which is a good idea after lugging around a 75-pound telescope).

First light with the Odyssey Compact was unusual, to say the least. Having no finder, I would lie on the ground and sight along the tube box. I must say, I got good at it fast. (I quickly added a 9x50 Celestron finder and a Telrad anyway!) The Ke27mm eyepiece and the objective’s 1152mm focal length make for a wide field of view. My first target was the globular cluster M13 in Hercules, an easy target that appeared as the faintest ball of haze in my 60mm refractor. I nearly fell out of my chair when I saw the cluster resolved into stars in the Compact!

Under a dark sky the Compact really shined. With this $300 scope, I was able to see the spiral arms in M81 and M66, the dust lane of M104 and the eyes of the owl nebula. At a star party, I had the opportunity to compare the views through my Odyssey with the views through a Celestron 8. The view in the Compact was at least as bright and as sharp as the view through the 8-inch SCT which cost 4 times as much. Okay, the C8 weighs half as much and sits on a motorized equatorial fork. No comparison there but considering the low-tech, minimalist nature of the Odyssey, I was very pleased.

At full aperture, the Compact performs very poorly when viewing the Moon, planets or double stars. Planets are tough to focus on and double stars become difficult to resolve blobs. The Moon is just too bright at any phase to even look at. With the previously mentioned 90mm stop-down mask, however, the Compact turns into a completely different telescope. The mask’s opening is placed to the side of the secondary mirror providing an unobstructed path to the eyepiece. The result is a 90mm, f/13 telescope that suffers no diffraction from a secondary obstruction and none of the color fringing common to all but the priciest apochromatic refractors. With a 10mm Plossl at 115x magnification, Saturn’s Enke gap is easily visible. The clouds of Jupiter are breathtaking and detail on the Lunar surface is dazzling.

In conclusion, the Odyssey Compact is an excellent and versatile, though low-tech telescope for the money as long as one is prepared to do some heavy lifting.