A Serious Binocular Telescope

Last March 2nd I experienced first light with a new telescope. Maintaining my tradition using Jupiter as my first-light object, I waited until well into dawn so that the giant planet could climb into the eastern sky and I could officially inaugurate the new instrument. But this time it wasn’t just one telescope; it was two. I was using my new 10-inch binocular telescope, the RB-10, made by JMI Telescopes.

Using a binocular telescope is the natural extension of the way most of us started out observing the heavens. My first look at the sky through an optical instrument was with my parents’ 7 x 50 binoculars during the summer of 1960. They gave me an excellent start.

From the small binoculars that introduce most of us to the night sky to the Large Binocular Telescope (LBT) that towers atop Arizona’s Mount Graham, twin-scope systems are powerful tools for astronomy. The LBT sports a pair of 8.4-meter (331-inch) primary mirrors supported by 580 metric tons of telescope.

In between the world-class LBT and the small binoculars that can carry us from baseball games to the stars, Jim Burr of JMI Telescopes has developed a line of sophisticated binocular telescopes ranging in size from 6- to 16-inch aperture. Each consists of two complete telescopes mounted together. All the adjustments needed to keep them precisely aimed and focused on the same object are made while you look through the eyepieces.

I quickly learned that observing with the RB-10, which I nicknamed Zubenelgenubi (view correction) after a famous double star in Libra, is different from regular observing in some remarkable ways. The most important one is that you face away from the object you’re looking at. You also look down (as if you were sitting at a desk reading a book), so right off the bat you’ve in a comfortable position using this instrument. Control buttons located underneath the eyepieces let you electronically adjust the interocular distance (space between the eyepieces), and the focus.

Starizona’s Dean Koenig helped me get the RB-10 set up. When he delivered it to my house, I thought we’d need a bulldozer to carry it from his van to the observatory. But as we gradually unpacked the box the main pieces were light enough for Dean to carry by himself. We had the RB-10 ready for observing in less than two hours.

While Burr recommends medium- to high-power eyepieces for the RB-10, I like low powers for comet hunting. I selected a pair of 25-mm Plossls that yield a field of view about three-quarters of a degree across and make comet searching eminently comfortable with this instrument. The RB-10 has also given me hours of fun observing solar system objects. The Moon hangs in space, awaiting its next spacecraft visit. Jupiter is a special joy. And when an Earth-orbiting satellite tracked through my field one time, it really appeared to hang below the canopy of background stars.

While my chance of making more visual comet discoveries are very slim these days, I always say that it’s the search that’s the fun part. With this new pair of 10-inch telescopes, the search will be even more fun than before.