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Binocular Mirror


This project came about due to a very long chain of events. It started off when I got Rukl’s Atlas of the Moon for Christmas. I went out one night to look at the moon and was having trouble deciding what to observe so I decided to try the Astromonical League’s Lunar Club, figuring it would be a good list of features to start off with. Well it turns out that most of the lunar observations are supposed to be done with binoculars. Now I’ve used binoculars for astronomy off and on for the past year, at first I didn’t really enjoy it but as the year went by I started finding more reasons to use the binoculars. So when I saw that the AL Lunar Club required binoculars I thought that sounded like a good idea and gave it a try. I started holding them by hand and that just wasn’t cutting it. So I then put them on a camera tripod, but it was still somewhat frustrating having to kneel on the ground to look at the moon through the binoculars.

I started thinking that perhaps I should build a parallelogram mount. That same night I was reading messages on the Cloudy Nights ATM message board (here’s the thread) when someone mentioned the Sky Window as being a good solution for mounting binoculars.I had never seen or heard of such a thing but immediately saw the benefit of such a system. I got excited, grabbed my binoculars, put them on a short tripod, took my wife’s makeup mirror outside and experimented. Although the results weren’t great I saw that this would work so I came inside and ordered a front surface mirror (Update: no longer has any contact info so doesn’t look like you can purchase from them anymore. I have 2 other sources listed at the bottom of the page).

The mirror came in a couple of days later and I spend a about 5 hours building the binocular mirror system you see here.

Construction Details

I built the mount as 3 separate components. The mirror tray, the binocular mount, and the base. Plans for each are available at the bottom of this page.

The mirror tray is constructed from 1/2″ plywood. I thought through a dozen designs before I finally decided that I wanted the mirror pivot point to be at the mirror center of gravity. This resulting in creating the side pieces shown below.

This picture also shows the mount for the binoculars. I wanted the ability to change this mount in the future in case I upgrade my binoculars. This might require adjusting the height of the support as well as the distance of the mounting point to the mirror. My solution was to make the binocular support removable. It bolts to the base so it allows me to change it if/when I get new binoculars.

The Base

The base is very straight forward. It has two supports to hold the sides of the mirror tray and a block (shown on the right) to attach to the binocular support piece. I added a 1/4″ t-nut to the middle of the base so the entire mount can be attached to a tripod.

This shows the first trial fit of the mirror tray and binocular support to the base before painting the base. (The mirror has a blue protective film covering it).

Here are some additional pictures of the assembled mount.


The following picture shows the white plastic mirror cover.


Mirror Base
Mirror Tray
Mounting Bracket

Links and Resources

Sky Window – A commercial version of my mount – source for inexpensive front surface mirrors (seem to be out of business)
First Surface Mirrors – haven’t tried them yet. If you purchase from them give me some feedback – another possible vendor

Florian’s Binocular Mirror – Another approach where the mirror is freestanding
Pao’s Binocular Mount – 2 different schemes for mounting the mirror
A Binocular Box – unique design where the carrying case converts into a table

Joe Carr’s Sky Window Review
Math Heijen’s Sky Window Review
Sky Window Yahoo User’s Group