Astronomy tests Denkmeier’s Binotron-27

High-quality optics and superb mechanics make this accessory a winner.
By | Published: August 27, 2013 | Last updated on May 18, 2023
Denkmeier Binotron-27
Denkmeier Optical’s Binotron-27 is a high-quality binoviewer. The two push/pull levers on the unit shown here operate the included Power x Switch system. // Astronomy: William Zuback
A number of excellent accessories exist for today’s visual observer, ranging from cameras to filters to incredible eyepieces. One of my personal favorites — and always a crowd-pleaser when I am doing outreach — is my binoviewer, and we’ll take a close look at a good one in this review. Simply stated, a binoviewer turns your single-eyepiece telescope into a binocular-like setup, allowing you to use both eyes.

Denkmeier Optical has produced fine binoviewers since 2001. Company founder Russ Lederman designed his initial binoviewer based on those he used with microscopes. He noted, however, that the optical configuration afforded an “extra” magnification around 3.5x, whereas the ones in microscopes added none.

Such a system-wide power increase was great for the planets but not for deep-sky objects. This led Lederman to different innovations, such as a lower-magnification (1.3x) compound optical system.

For the Binotron-27, Denkmeier literally went back to the drawing board and came up with an all-new design. Engineers were able to incorporate several refinements to earlier binoviewer designs that make this model user friendly while still affording spectacular views. For a start, the Binotron-27 incorporates prisms 27 millimeters across, which affords each a 26mm-wide clear aperture.

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