Sunday, May 18, 2014

A DIY Binocular Mount

Thanks to a change in plans--a wedding I want to attend is on the same Saturday as the Wisconsin Observers Weekend--I am going to go to this year's Nebraska Star Party. No offense intended to WOW, but NSP is a bit of a bigger show with more people and darker skies. NSP begins as the annual Jeffers Petroglyphs party ends, so I'll be able to save a couple of hours of drive time by going straight from Jeffers to NSP.

But what to do at NSP? I'll have my imaging gear from Jeffers with me, but maybe I should just make my first NSP a strictly visual affair. All that really dark sky, you know!

I've come into possession of an old pair of Celestron binoculars, their 11x80 Giant model from the 1990s:

This is not the model that was labeled "Comet Hunter" or "Comet King" apparently to cash in on Halley's Comet in 1986. What reviews I can find for this later model are mixed.

Good features from my standpoint:

  • It was free
  • It has a wide FOV (4.5 degrees)
  • It comes with a mounting bracket. 


  • Probably not the greatest optical quality
  • Heavy (6.7 pounds) 
  • Exit pupil (~7mm) that is too large for my old eyes. I'm 60, and although I haven't measured, I would guess my pupils don't open past 5mm. This means that some of the objective size is being wasted, but some people suggest this has a small silver lining in that one's eyes can move a little laterally and stay in the light.
My past experience with large binoculars suggests that a mount is a very good thing to use for steadiness and comfort. A little googling turned up this plan, which I am adapting to the top of my CGEM tripod. The CGEM tripod has two threaded holes for mounting the azimuth post. These are perfect for attaching a base plate. In my case I'm changing the plan to substitute a 3/4" piece of hardwood for the 3/8" aluminum plate. The rest will be pretty much as the design suggests.

I was unable to find the nice round counterweights seen in the explanatory pictures, so I'm using lead scuba weights from the appropriately named Lead-co USA. Construction begins next week.

An update on May 20: Lead-co uses fixed-cost USPS mailing boxes, and I had paid for a medium sized-one. It turns out that the weights I bought fit in the small box, so Lead-co refunded the difference. Nice!