One of the well known negatives of binoculars is the challenge of holding them steady. Mounting them on a tripod is an option, but this can make viewing targets at higher altitudes uncomfortable. One solution is the binocular mirror mount.
A binocular mirror mount is a device that securely holds your binoculars in a comfortable downward-facing position pointing towards a mirror that presents a reflected view of the sky.
Commercially produced binocular mirror mounts can be purchased, of course, but since the devices are relatively simple – mechanically speaking – they can be quite easily constructed using basic materials and a few tools.
This article will show you how.
The mount in this article is made from two sizes of aluminium angle section, plywood sheet, some standard fixing hardware and a front reflecting, or first surface, mirror.
Regular mirrors have their reflective coating on the rear of the glass.
They produce a slight double image, which although is imperceptible in general use, would compromise a magnified view.
First-surface mirrors can be sourced from many specialist suppliers and usually made to your requested size.
The mirror must be sufficiently optically flat to ensure that the paths of light reaching the objective lenses of your binoculars remain parallel.
It’s therefore important to make the supplier aware of its intended use when ordering your mirror.
The mount can either be rested on a flat surface or attached to a telescope tripod with a flat top and central mounting hole.
Both options are possible as the mount uses a long coach bolt that acts as a supporting leg on a flat surface or a bolt to attach the mount to a tripod.
Using a tripod is often a more convenient option than trying to find a suitable flat surface outdoors that’s at a comfortable viewing height.
To work with this mount your binoculars must have a threaded, central mounting point for which you’ll need the correct hand screw.
This mount was designed around a 12×60 pair of binoculars, but it is also compatible with the more commonly used 7×50 or 10×50 variants.
Tools – Hacksaw, vice, engineering square, pencil, drill (with 4, 6 and 8mm bits), small adjustable spanner, screwdrivers, fine metal file, sandpaper.
Materials – One 1,425mm length of 25x25mm aluminium angle and one 380mm length of 25x40mm, both 3mm gauge. A 145x220mm first surface mirror, a piece of 12mm-thick 225x150mm marine plywood, a CD.
Sundries – One M8x180mm coach bolt with nut, a wing nut and two 25mm penny washers, two M6x30mm nuts and bolts with four washers, 16 M4x15mm machine screws (four need to be countersunk), M4 nuts and washers, silicone sealant.
Using the mount
When attached to the mount, your binoculars are secured at an approximately 45° downward angle.
You adjust the view up and down by simply tilting the mirror.
The open frame design allows you to position the mirror by holding its plywood mounting cell, meaning that there’s no need to touch the reflective surface of the mirror.
The azimuth is altered by rotating the entire assembly, either on your chosen surface or around the axis of the central tripod mounting bolt.
Because the underside face of the mount’s supporting angle section sits on the flat top of your tripod, a CD is inserted in-between to act as a washer – reducing friction and minimising wear on the tripod’s top face.
By simply tightening their respective fixings, the friction for the mirror pivot and tripod mount can be easily adjusted for the ideal balance between ease of movement and rigidity while viewing.
In use, the reflected view initially makes locating celestial objects slightly more challenging than if you were holding your binoculars.
But once you’ve mastered the technique of using this mount, you may well find yourself gazing downward into space instead of upwards for many hours!
Cut the 25x25mm angle into two pieces of 350mm, two of 280mm, two of 25mm and one of 90mm.
Cut the 25x40mm angle to 380mm.
Drill and bolt the 350mm and 280mm pieces together using the M4 fixings to form the main rectangular frame.
Drill two 6mm holes through the corner of the 25x40mm angle at 45° and 12mm in from each end.
Then, file flats on the outside corners around the holes.
Also, drill an 8mm hole in the centre of the widest face for the coach bolt.
At one end of the main frame, drill two 4mm holes as shown.
Then, drill an 8mm hole in the 90mm piece for your binoculars’ mounting screw.
Using the 4mm holes in the main frame as a guide, mark, drill and fit the 90mm piece using 4mm nuts and bolts.
Drill three 4mm holes in the two 25mm pieces and bolt them to the plywood using the M4 countersunk screws.
Then, drill M4 holes in the sides of the main frame and mount the plywood on its brackets using 4mm nuts and bolts.
Invert the whole assembly, then, using the 25x40mm angle as a guide, mark and drill through the main frame and attach it using the M6 nuts and bolts.
The mirror can now be attached to the plywood using silicone sealant and left to cure.
For tabletop use, attach the coach bolt head downwards through the 8mm hole in the 25x40mm angle using the M8 nut, wing nut and penny washers.
The bolt serves as a supporting rear leg and can be used to secure the mount to a tripod.
Will Davis is a technical service manager in the sound industry and a keen practical amateur astronomer.