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Accessories: Binoviewer

The Burgess Optical Binoviewer is a lightweight stereo binocular viewer adapted for use with telescopes. The binoviewer includes eyepiece holders that accept a matched pair of eyepieces to allow comfortable two-eyed viewing through a telescope. Three models have been released of the Burgess Binoviewer: the Model A and Model B, which have been discontinued, and the Model C, currently in production.

Use and Operation of the Binoviewer

Using the binoviewer is as easy as inserting the binoviewer nosepiece into where a 1-1/4" eyepiece would normally be inserted into the telescope. After the binoviewer is secured, insert a matched set of eyepieces into the eyepiece holder.

Enjoy two eyed viewing by focusing the image in one eyepiece in the normal manner. After that eyepiece image is focused, rotate the eyepiece holder of the other eyepiece to obtain focus in the second eyepiece.

A matched set of eyepieces is no more than just two eyepieces with the same focal length and of the same type, for example a pair of 17mm Plossel eyepieces. The helical eyepiece holders easily adjust for eyepieces of the same type that are not parfocal.

Merging Images: Each Burgess Optical binoviewer is tested by Bill Burgess for collimation before being shipped. A properly collimated binoviewer allows images to be merged easily when using an assortment of pairs of eyepieces.

Occasionally, the images seen in each eyepiece may not merge, that is, they do not appear as a single object when viewed with both eyes. This typically occurs when using short focal length eyepieces, which have a small exit pupil. Longer focal length eyepieces with their larger exit pupils typically allow merging with no difficulty. If you encounter problems merging images, read our Binoviewer Merging page.

Reaching Focus: Currently, the Burgess Binoviewer does not come with a corrector (commonly known as an OCA - an Optical Corrector Adaptor). In order to reach focus in a telescope, the focus tube needs to be racked in an amount equal to the optical length added by the binoviewer, which is about 4 inches (100mm). For more information, read our Binoviewer Focus page.

* The early Model C binoviewers had 20.5mm of clear aperture, whereas the later ones are 22mm. To determine true clear aperture, measure the opening at the bottom of the eyepiece holder; however, caution must be exercised because there is optical glass immediately below that opening. Another method of measuring clear aperture is to direct a parallel light beam through the binoviewer and measure the diameter of the projected spot. Diverging light beams will give misleading results.

Available accessories include a 1.9x corrector (OCA) and matching eyepieces, of which we have many to offer.

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