300-mm Binoculars MkII

The Bolton Group

The MarkII binocular are here. Weighing just over 100 pounds and breaking down into 4 easily assembled parts makes them truly a one-person intrument.

STOP PRESS - these have been sold.

Ready for action at Kelling Heath Star Party September 2006. The views there were simply "out of this world" - stars were pin-point and deep-sky objects just jumped out of the eyepiece.


There is no comparison to using two eyes - perhaps that's why we have 2. The original 300-mm binoculars provided the ultimate in viewing experience - the views were simply mind-blowing both on deep-sky and the planets! They required no ladders - you are safely on the ground no matter where they point. No wonder they won best in star party at Kelling Heath 2005. But......... they were a serious instrument that required a two man set-up. The experience gained with the 8.5 inch ultra-lights set thoughts running.....

Could the ultra-light principles be applied to the 300-mm?

Could the wonderful new interocular adjuster be used?

Could the clever bottom bearing reduce weight even more?

But they must be rigid and hold collimation - virtues that set the 300-mm apart from commercially available binos. We will not tolerate wobbly telescopes.


The project was begun with a target of having them finished for Kelling Heath September 2006, which was achieved with 2 months to spare - sufficient time to try them out and tune them to perfection. Transport is very easy with an ordinary sized hatchback. They separate into 5 components making them suitable for one man assembly and the total weight is around 105 pounds. There is an upper cage; a lower cage, the mount and 2 mirror cell/mirror units. All assembly is with easy thumb nuts - no fiddling around. These pics hopefully explain the construction.

The 4 main components. The lower cage and mount can also dis-assemble.

Attaching the mirror cell complete with mirror - note captive thumb screws are used.

Mirror collimation is by the brasss thumb screws

Rear view of both mirror cells

Close-up of one of the mirror cells

Note adjustable clutch on altitude bearing

New interocular adjuster

Easy load into Toyota Corolla - white box holds both mirror cells complete with mirrors

Captive thumbscrews for easy assembly - nothing to lose in the dark.

The Business view!

Brian and Gerald complete the simple one man assembly

Side view of completed binos

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