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Bushnell binocular telescope attachment called the booster (1 Viewer)

John Dracon

John Dracon
One of the pleasures of being older and retired and immersed in the hobby of collecting and using binoculars is finding a piece of optics which is a 2.5 X extender designed for specific Bushnell models. My Bushnell archive had a multi page brochure (1969) describing such an apparatus, which is inscribed on the body as the "booster." It is designed to fit Bushnell 7x35 models.

Bushnell had made one for their riflescopes, as did Leupold. But this booster or extender is entirely different from the riflescope piece. I managed to pick up several designed for binoculars and have been "playing" with them and was particularly interested in how they would compare to the Bushnell Elite 2.5X in a kind of of an optical show down. I was in for a big surprise in several ways.

Now the Elite 2.5X is a different design. It slides over the oculars, whereas the Bushnell booster slides over the objective rings. A number of forum readers have felt that the Zeiss 3x and Elite 2.5 X are the best optically of the extenders available. The Swarovski 2x extender is high quality and has the screw-on feature which keeps it centered and safe from falling off. I have used them all for several years.

I expected the 44 year old Bushnell boosters to be inferior optically. I was mistaken. The magnified images are excellent, IMO superior to the current extenders. I wasn't prepared for that.

The Bushnell booster slides (friction fit) over the objective rings of a number of Bushnell binoculars. Bushnell marketed three diameters: 2.09 inch (53mm); 1.97 inch (50 mm); 1/83 inch. I have the first two models. Their objective lens diameter differ:the 53 mm is 33 mm and the 50 mm is 32 mm.

The 53 mm model fits all of the custom line including the Rangemasters while the 53 mm model fits the Featherlight and Banner series.

But the biggest shock was the performance of an old odd pair of IF Bushnell 7x35 with a 7.3 fov. Using the Air Force optical chart and live critters, e.g., deer, horses, and cattle, the magnified images were superlative. Yet, but here is the "kicker." The prisms show the square grey box edges. Is it possible that what is called the BK-7 prisms aren't so inferior after all?

I have an old Bushnell Featherlight which is an 8x30 Zeiss B clone that has startling sharp resolution, Yet, it has BK-7 prisms. True the colors are less vivid, and it is single hard coated, but the resolution is astonding. I would appreciate comments from those of you who are collecting vintage models if you have run into this phenomenon?
 
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