Oregon Star Party 2012 Telescope Walkabout

by Mel Bartels, pictures by Barbara Bajec

This year's walkabout, the 17th annual, featured accessories, a bino-viewing platform, a ball tracker and a carbon-fiber telescope. I also include a telescope left out of the walkabout because of the extreme heat that afternoon.

For those who have not participated, we gather a large crowd at the appointed time and walk from telescope to telescope as a group. The builders talk about the telescope and their experiences: what worked, what didn't, what had to be done over, what can be improved, where the idea came from, what's next, and so forth. Since there are no awards involved, the questions and answers are more open and useful. Presenters on subsequent walkabouts have mentioned that their inspirations have come from earlier walkabouts.

The Oregon Star Party walkabouts in particular have shown the first single upper ring Dobsonian, the first flex rocker, the first string telescope, the first popular altazimuth tracking system, the first amateur direct drive motor, four 40+ inch [105cm] telescopes, airline transportable scopes, folding scopes and binocular telescopes, the largest of 22 inch [56cm]. Steam punk refractors of gleaming brass, scopes that took many years to complete, scopes that were finished the day before and accessories and aids have also been featured.

Chuck Dethloff and his wife Judy (founders of the Oregon Star Party) are among the most experienced observers on the planet. Chuck has spent years improving his observing experience on their 24 inch [61cm] and 16 inch [41cm] telescopes. He showed us several of his accessories. He uses a series of painters drop cloths that range from the car to the telescope to cut down on dust - it makes a significant difference. He nails the drop clothes into the ground with penny nails that can be pulled out later. He also uses a shoe brush at the entrance to his tent, which visibly cut down on dust. Chuck also uses a portable blower to blow dust off of his telescope including the primary mirror. He uses a Kydex ring around his azimuth axis to protect it from blowing and kicked dust, preserving the smooth motion of his azimuth bearings. He also uses a simple two piece step stool for observing when the eyepiece is just above the eyes. He uses a specially constructed eyepiece shroud that slips onto the base of the eyepiece in order to cut out stray light from his eyes. It does make a difference in detecting faint stars and detail. Chuck also has placed a circular filter wheel just below the focuser so that he can quickly switch between filters. And finally, he's added a drive system to his altazimuth Dobsonian telescope, which results in as much time needed with the object centered in the field of view, increasing the detectability of the object and its detail. Summed together, these aids make for an enhanced visual observing experience.

Bill Briggs, who has been on the telescope walkabout in prior years with innovative telescopes, demonstrated his heavy binocular viewing platform that not only holds the binoculars on their stand, but also his observing chair. He designed a heavy parallelogram holder for the binoculars using parts from Boeing Surplus in Seattle. The binocular is attached with a heavy commercial head rated at 30 pounds. He dampens the entire assembly by simply touching it with a finger for a couple of seconds.

Jerry Oltion, noted science fiction writer and telescope innovator, showed his split pupil finder and his inexpensive ball scope tracker. The split pupil finder relies on the eye, located behind the top of the lens, looking simultaneously through the lens and over the lens and at the sky. The lens projects an image of a pointer painted in glow paint onto the sky. The unity finder is incredibly inexpensive and easy to make. It's accurate to a fraction of a degree. Note that his giant demo unit does not have a clipped flat upper lens edge to look over and under through. Here he is holding the large demo unit and the much smaller working finder.

The ball scope tracker is a simple roller geared with plastic gearing operated by a DC motor so small that he has yet to replace the batteries after three years of heavy use. The mount is simple to align: a visual alignment by standing behind the mount and aiming the arm with the slidable motor so that it tracks at a range of latitudes at Polaris. The motor powered roller is on a polar axis. Objects stay in the field of view for hours regardless of scope or eyepiece orientation; plus there is no Dobson's hole. For more, see http://www.sff.net/people/j.oltion/trackball.htm

Chris Tribe showed off his impressive 14.7 inch [37cm] carbon fiber telescope built over a number of years. It's mainly composed of carbon fiber fishing rods bought at low cost and core-ply upper and bottom ends wrapped in fiberglass. The fishing rods are linked by wooden gussets. The mirror drops into the centerless azimuth ring bearing which lowers the eyepiece height. Overall weight is 31 pounds, the quartz mirror made by Mark Cowan weighing 11 pounds. Chris ended by casually lifting the tube assembly as it it weighed nothing, which is almost does, and by leaning heavily down on both ends of the tube assembly which did not deflect in the slightest.

Because of  the extreme heat (100F, 38C), I ended the walkabout at this point, an hour into the session. I left out my re-built 13 inch [34cm] ZipDob which I include here. The redesigned mount features two folds instead of three and a smaller volume than before. The scissor truss arms with stabilizer wood plate work quite well.