Giant Binocular Viewer from Baader Planetarium (BPBINOV)

The BPBINOV model is no longer available. This information is provided for historical reference only.

Several years ago, Carl Zeiss Jena manufactured an excellent Binocular Viewer which we were pleased to offer to our customers. When the amateur telescope division was closed in the Fall of 1995, the binocular viewers were no longer produced. In 1996, the Baader Planetarium company took over service for Zeiss telescopes and also acquired the rights, patterns and drawings for the Zeiss Binocular Viewer.

We are very pleased to offer this fine Binocular Viewer once again. The optics, body and mechanical works are produced and assembled by Baader Planetarium according to the original specifications by Carl Zeiss.

This accessory was developed specifically for amateur telescopes unlike others, which were adapted from microscopes (small prisms designed for .965" eyepieces). The large multi-coated prisms allow full illumination of 1.25" oculars. Interocular separation adjustment (eyepiece spacing) does not affect focus. The interocular distance can be adjusted from 55mm to 75mm.

The binocular viewer has a removable 1.25x compensating optical element (located under the bayonet in the illustration) which eliminates the slight color error and spherical aberration that a prism beam splitter naturally introduces into the light path of all binocular viewers. This element (also known as a Glasspath Compensator) was designed by Roland Christen and is essential for telescopes with fast focal ratios. The Giant Binocular Viewer is the only one on the market with this feature. It allows you to enjoy wide-field, low-power views of deep-sky objects, as well as high powers. We also offer the 1.7x (BP4B) and 2.6x (BP4C) Glasspath Compensators.

While the binocular viewer works extremely well for showing subtle features on the lunar surface and for bringing out planetary detail, we recommend that you thread in part of our Convertible Barlow (BARCON), with an effective magnification 2.4x, to the front of the viewer for critical high-power observing (such as double star observations). This optional accessory lens narrows the incoming beam and results in the sharpest possible images at the eyepiece end of the binocular viewer. Another excellent option is the Fluorite Flatfield Converter Barlow (FFC) also available from Baader Planetarium. We suggest that you review the entire range of options in the FFC System (PDF document).

The Giant Binocular Viewer includes the viewer itself with built-in (but removable) 1.25x compensating element (BP4A), prism diagonal (BP1), and the 2" barrel (AP16T) as shown on the assembly diagram. Optional items include: eyepieces, the Convertible Barlow (BARCON), items from the FFC System and filters.

The back focus requirements will vary depending upon your configuration. Please note that this viewer may not reach focus with some instruments, including some earlier models of our refractors. Determine the back focus of your instrument by measuring the distance from the 2" opening of your scope to the focus point.

All units shipped after February 23, 2000 include eyepiece stops and can be used with any 1.25" eyepiece, regardless of the length of the eyepiece barrel - even with filters.

Additional Specifications:

Clear Aperture: 1.1" at the prism entrance w/o the compensator and 0.96" with the compensator.
Weight: With Barlow (without diagonal): 1 lb 14 oz

WARNING FOR BINOCULAR VIEWERS SHIPPED PRIOR TO 2-23-00: Eyepiece barrels longer than 1.2" will strike the prism within the Binocular Viewer. This includes the TeleVue 22mm Panoptic and these TeleVue Radians: 5, 6, 10, 14, 18mm. Remember that filters add length to the eyepiece barrel.

Solution for Binocular Viewers already purchased: Astro-Physics will provide an eyepiece stop that the user can install on his/her Binocular Viewer. We have supplied these to all customers who purchased these viewers directly from us prior to February 23, 2000. If you have moved, purchased the unit from a dealer or purchased the Binocular Viewer as a used item, please notify us.

This assembly diagram shows how the the Binocular Viewer is used in various configurations. It also contains information regarding back focus requirements. Click on it to enlarge.

Recommended Accessories

Convertible Barlow (BARCON)
1.75x Glasspath Compensator (BP4B)
2.6x Glasspath Compensator (BP4C)

48mm Moon & Skyglowfilter (BPMS2)
Accessories from the Baader Planetarium FFC System
1.25" eyepieces. We typically use a set of Plossls in a medium power range. A set of 19mm or 22mm Panoptics eyepieces are particular favorites of our binocular viewer customers. Note that the 22mm Panoptics may not be suitable for viewers with wider noses. TeleVue Radians are also favored by many. Please call us for your TeleVue eyepiece purchases.

Additional products from Baader Planetarium


Back to top

Copyright © 2003, Astro-Physics, Inc. - All Rights Reserved
This page was last modified: December 16, 2011

Astro-Physics, Inc.
11250 Forest Hills Road, Rockford, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847