17.5 inch Binocular

· F/4.5 17 ½ inch primary mirrors

· 4.25 inch minor axis secondaries

· 1.5 inch minor axis tertiary mirrors

· Lumicon helical focusers

· Upper cages rotate to permit adjusting interocular distance

· Easiest eyepiece for viewing is 20 mm Meade Erfle – this gives 100x

· Meade 9 mm super wide field eyepieces yield 225x

· Limiting magnitude about 15.6 – Stephan’s Quintet ranging mag 14.8 to mag 15.3 can be seen clearly with direct vision

· Optical paths collimate independently

· One tube moves left right while other tube moves up/down, permitting convergence of images “on the fly” while observing – this essential for higher magnification.

· Entire scope weighs 175#

McDonald Observatory 1992

The 17.5” binoc was a workhorse for 7 years and went to Texas Star Party for 5 years. It provided great views – here’s TSP observer quotes from Sky and Telescope October, 1992, “I stroll over to the silhouette of a large pair of Newtonian Binoculars. The owner explains the necessary adjustments. M51 is directly overhead. I center it, carefully focus for each eye and make one final adjustment to converge the images. Oh, my! Poetry of light! Experimenting, I close one eye and see just a grainy image. Both eyes reveal graceful spirals of textured creamy light.” And the second observer, “I glance at chart 150 of Uranometria which shows a faint, tightly packed cluster of galaxies—the Coma Cluster near Beta Comae Berenices. They should be quite faint, perhaps beyond the reach of the 17 1/2” binocular telescope before me. At first I see only two galaxies. Then I shift the view and gasp. There they are—at least 12 faint, fuzzy ovals of light tilted every which way, almost touching. It’s an archipelago of remote islands in the vast sea of space.”

I finally sold the scope to some folks in Utah. Setup took about 45 minutes and teardown another 30, so the scope went out only on “great” nights – despite the aperture and all else, there is something to be said for the scope that gets used the most and that is often the smaller more portable instrument. The big scope got used about 1 time per month over the years. My 6 inch binocular which requires no setup and is always “ready” for viewing is out under the stars probably 4 or 5 times each month over the last 4 years. But, still miss seeing those 15^th mag galaxies!

· My friend, Bill Spargo built this 13.1 inch binoc using my design

· The control knobs for the x/y tube adjustments are detailed

· He added handles to make upper cage rotation easier

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