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RB-66 6" Reverse Binocular Telescope

RB-66 Reverse Binocular (63,607 bytes).
"seeing the Double Cluster in the RB-66 left me feeling weak at the knees and misty eyed"

Evolution of the Reverse Binocular

Amateurs telescope makers and professional manufacturers have devised ways to assemble two telescopes to work as one binocular for some centuries. The binocular arrangement provides a way to observe much more detail, with improved comfort and often presenting an illusion of three dimensional views.

The binocular telescope usually consists of two relatively long and narrow refractor optical tubes in parallel, aligning them to work as one system. The Carl Zeiss firm in Germany was the most successful at this implementation. From the turn of the 20th century until the 1930's Zeiss made binocular refracting systems in apertures from 60 mm (2.4) to 110 mm (4.3 inches), and later in much larger observatory systems. Company Seven now offers large ("giant") refractive binoculars of up to 150 mm (5.9 inch) aperture; these present striking views but can cost in excess of $10,000. And since these binocular eyepieces are fixed somewhere on the order of between 20 x to 40 x, there is no way to change magnifications.

The RB-66 Reverse Binocular Optical Arrangement

It has long been realized that more and more light gathering power reveals more of the celestial wonders to the eye. And an economical way to obtain light gathering power is with a reflecting or Newtonian arrangement. In order to provide cost effective aperture, the optical arrangement of each RB optical tube assembly is Newtonian. While an English mathematician originated the concept it was Sir Isaac Newton who first made a working model in 1668, and he continued refining the design well into at least 1671. The larger of the two is a Parabolic mirror and this is the factor by which most telescopes are characterized. Hence an 10" telescope has a primary mirror of 10 inch (250 mm) in diameter.

Amateur telescopes makers experimented with ways to make the Newtonian design into practical binocular. By the 1980's the most notable of these was Mr. Lee Cain who demonstrated his 13.1 and later a 17.1 inch reverse binoculars to astonished viewers at Star Parties in the USA. Mr. Cain dealt with some of the complicated aspects of making this work with techniques and materials that require some bit of dedicated understanding and patience on the part of the owner of those systems.
Optical arrangement of Newtonian Reflecting telescope (38,882 Bytes)

Right: Arrangement of Newtonian reflecting telescope (38,882 bytes). Click on image to see enlarged view (187,513 bytes)

The RB-66 consists of two compact 6 inch (150 mm) aperture f/5 Newtonian optical tube assemblies supported precisely in parallel within a machined frame, supported by an alt-azimuth platform. The optical tube is an open truss frame work made of aluminum stock finished internally in an anti reflection paint, with a lightweight molded exterior white shell. This assembly holds optical collimation well even with temperature or humidity changes. This tube design permits the designer to select a smaller secondary mirror/obstruction than might otherwise be needed. And this keeps the assembly lighter in weights.

The Primary mirror of the telescope is precisely mounted in a Cell at the rear of the telescope. The light entering the telescope is gathered and then reflects forward in a converging beam, to the Secondary Mirror (an elliptical flat) that is positioned near the front of the telescope and tilted at a 45 degree angle. The light from the Primary Mirror is reflected by the Secondary out to the side of the telescope and through the Focuser to form a virtual image at a point beyond the focuser. An eyepiece to enlarge the image for viewing is slipped onto the focuser to view or capture the image.

Parabolic Primary Mirror of a telescope
Left: Parabolic Primary Mirror of a Newtonian telescope in a Cell (16,559 bytes). Click on image to see enlarged view (68,383 bytes).

The Primary Mirror of the RB-66 is made of Pyrex® glass. The American firm Corning Incorporated developed Pyrex® a well proven material which has been marketed since 1915. Pyrex® is a sophisticated borosilicate glass composition made of Silicon, Boron, Sodium and Aluminum. It provides good chemical, thermal, mechanical and optical properties. Its density is 2.23 g/cm3. This material can be polished to provide and hold a high quality of view, and provides stability and optical performance better than mirrors in most telescopes sold anywhere near this price range. We have been quite pleased with the performance of these mirrors.

A well made reflecting telescope can offer the best view per the dollar of the faint, deep sky objects where light gathering power is essential. Light gathering power increases are more important and come quicker than one may think; consider that each optical tube of the the 6 inch RB-66 may show objects about 335X fainter than the unaided eye, while each optical tube of the larger RB-10 provides about 900X the light gathering power over the unaided human eye. For serious photon appetites, we also sell the RB-16 which weighs in with about 2,600X the light gathering power over the unaided human eye at each of the two eyepieces - in astronomy size can matter!

The RB-66 Reverse Binocular Telescope As we mentioned before, this is not an entirely new concept since it has been around in apertures from 10 inch to greater than 20 inches, and popularized by experienced amateur telescopes makers. However, in the Spring of 2003 with the introduction of the 6 inch f/5 RB-66 JMI became the first manufacturer in the world to make the concept practical, and transportable for the enthusiast.

The Reverse Binocular permits an observer to look down into the eyepieces, either while comfortably seated on an observing stool or while standing and see what is in the sky behind you. This is far more comfortable than straining to look up as is the case with a traditional straight through view or inclined angled eyepiece binocular. These RB systems consist of two precisely joined Newtonian telescope optical tube assembly, installed in an alt-az mount creating a very compact and comfortable viewing experience.

The available models manufactured by JMI are 6" RB-66, the 10" RB-10, and introduced in the spring of 2005 - the 16" RB-16 (U.S. Patent Pending). You may see examples of these if you visit our showroom.

Right: JMI Model RB-66 Reverse Binocular Telescope, viewed from front right (39,671 bytes).
Note the optical tube covers in place, the height adjustment handlebars, and just below the integral wheeled stand.
Click on image to see an enlarged view. Many other images of the RB-66 are available below.

In order to make the Reverse Binocular Telescope work for the amateur, JMI had to overcome a number of difficulties one normally encounters with the Newtonian telescope. The most well known concern is the need to precisely center then tip and tilt the the optical components into precise alignment. The overall alignment of the one optical elements to one other, and their placing the focal plane (the point where the image comes to focus) at the correct position beyond the focuser are critical. All of this is exponentially compounded when one is working to keep not one but two telescopes aligned to each other as well. JMI had to eliminate any possibility of flexure of these systems when panning from one area of sky to another.

To attain this JMI engineered a truss framework to support the RB components, then incorporated geared and motorized mechanisms to permit the user of the RB system to align the optics while observing through the eyepieces.

And JMI engineers worked through many prototypes to arrive at a system which is not only user friendly, but in sizes up to the RB-66 and RB-10 are easily managed and transported.

What is an Alt-Az Mount?

The RB-66 Reverse Binocular is provided with an "Alt-Az" or altitude-azimuth moving mount. This mount moves in altitude (up and down) on a horizontal axis, and in azimuth (left and right) on a vertical axis something like a gun turret on a tank. By comparison, an equatorial mount is essentially an alt-az mount that is tilted to match your latitude, allowing a telescope to track the stars with the addition of a simple clock drive Both types of mounts have their advantages Which one is best for a particular situation depends mostly on how one intends to use the telescope.

A critical aspect of the design of this mount is that it moves smoothly and with uniform effort throughout in elevation and in azimuth, with no rough spots or binding along the way. This is the only way that a mount such as this can be truly practical for the observer who seeks a telescope that "gets out of the way" between him and the night sky.

RB-66 Standard Features:

  • Two JMI Motorized Focusers, Crayford design for smooth and easy precise focusing
  • Motorized optical alignment of the optical tubes with the push of a button
  • Two 20mm 1.25 inch Dia. eyepieces providing a 1.5 degree actual field of view*
  • "Star Pointer" Night Sight illuminated Red Dot sight to facilitate initial set-up or "star hopping"
  • Battery Power operation powered by a common 6 volt DC 4.5 amp-hour sealed rechargeable battery housed in the Binocular assembly. A 110 VAC/60Hz or 220 VAC/50Hz charger (please specify) is provided. The anticipated battery life will be measured in months.
  • Integral Handle Bars:
    • facilitates easy movement of the RB-66 to find and follow objects across the night sky,
    • provides convenient space for installation of MAX computers or other digital position readout devices,
    • incorporate easy to reach, hard to confuse buttons for focus and alignment,
    • retract in for storage.
  • Protective lightweight cover (white, or available in black by special order)
  • JMI's celebrated quality of durable and appropriate construction

* By customer request, Company Seven can delete and credit the cost of the two provided eyepieces against an upgrade to the superior TeleVue 24mm Panoptic eyepieces. The 24mm Panoptic provide a wider 2 degree true field of view, tack sharp images across the entire field of view even when used of relatively "fast" telescopes as the RB-66, and good observing comfort. The telescope can accept a wide range of 1.25 inch oculars.

Customer Comments about RB Instruments

"Thanks for reinventing astronomy.... It's a whole new ballgame now." (Ralph Holt)

" RB-66 is terrific. You've invented a great instrument." (B. K.)

"A group from the Fort Wayne Astronomical Society, while in New Mexico this past September, put our scopes aside and rented JMI's RB-66 for a night. We all agree with Phil Harrington's assessment of the binoscope's spectacular seeing in the night sky..." (Ron Kerr, Letters, June 2004 Astronomy)

"Few binoculars can compare to the RB-66. ... If you're looking for breathtaking low and medium-power views of star fields, nebulae, star cluster, and the Moon, give the RB-66 from JMI serious consideration. For observers who appreciate the wonderful views seen only through a true binocular telescope, the RB-66 is a real bargain." (Phil Harrington, Telescope Review, February 2004 Astronomy)

"The Swan was hanging suspended in a 3D star field with the bird's wake clearly visible, awesome!" (Okie-Tex Attendee)

"I could see far more than just the core of M101 ... hinting at spiral structure. This is impressive contrast for a 6" scope." (Okie-Tex Attendee)

"A professor and several of us serious astronomers spent the night trying to find words to describe what we were seeing. We were dumbstruck, blown away,'s unspeakable. The views are beyond the power of mere mortals to put into words The RB-66 changes everything. It is the greatest piece of optical equipment I've ever looked through." (Paul Carmody, RB-10 owner and customer of Company Seven who traded up from his 6" RB-66)

"The RB-66 is a deep space scope I have used it to look at galaxy clusters with absolutely breathtaking results. Imagine seeing four or five 12th magnitude galaxies hanging as if suspended in mid-air!!  You can see the wake of the Swan Nebula without a filter Field of view for this scope can be determined by considering that it is just two 10" f/4.7 scopes, so you can use the normal formula... The included 25mm eyepieces deliver about 48x magnification. Using a higher power only means the 'tweaking' or rather 'refining' needed takes a few extra seconds (that's right, seconds, remember everything is motorized!" (Tom Johnson, Production Manager, JMI)

"seeing the Double Cluster in the RB-66 left me feeling weak at the knees and misty eyed" (remark at a local star party when Company Seven brought an RB-66)

Optical Arrangement Parallel Newtonian Reflector
Aperture 6 inch / 152 mm
Focal Length 30 inch / 760 mm
Focal Ratio f/5
Mirror Substrate Pyrex®
Elliptical Secondary M.A. 1.6 inch / 40.6 mm
Mirror Coatings Durably aluminized and overcoated
Cumulative Light Throughput (each OTA) Approx. 350X the light gathering power of the dark adapted, unaided human eye

Optical Tube Spacing 9.5 inch / 24.1 cm
Interpupilary Spacing Variable from 2 to 3.25 inch / 51 to 82 mm
Focuser 1.25 inch Dia. / 34mm
Tube Alignment Mechanism Variable motorized x and y axis
Power Requirement 6 Volt DC
Battery Provided Internal 6 Volt DC, 4.5 Amp Hr Battery
Battery Charger Provided Customer choice either 115 or 220 VAC
Optical Tube Mount Alt-Az with Field Tripod
Bearings Derlin
Binocular Tripod Height Range 26 to 42 inch / 66 to 106 cm
Binocular Length 30-1/4 inch / 76.8 cm
Binocular Width 24.5 inch / 62.2 cm
Binocular Depth (stowed) 11 inch / 28 cm
Binocular Weight 49.4 lbs. / 22.45 kg
Tripod Weight 9.6 lbs. / 4.4 kg
RB-66 Shipping Dimensions 36-1/2 x 14-3/4 x 29-1/4 inch / 92.7 x 37.5 x 74.3 cm
RB-66 Shipping Weight 85.4 lbs. / 38.8 kg
RB-66 Tripod Shipping Dimensions 30-1/2 x 10-1/4 x 11 inch / 77.5 x 26 x 27.9 cm
RB-66 Tripod Shipping Weight 12.2 lbs. / 5.6 kg

* Specifications are subject to change without notice. For information about the price of the Reverse Binoculars, their accessories and upgrade please refer to below and to our JMI Price page. Or you may contact Company Seven to obtain current pricing and shipping options and cost estimates.

RB-66 Optional Accessories

    Carrying Case lightweight, hard shell case with foam lining:

    Highly recommended for routine transporting $419.00

    Next Generation Computer system:

    Choose the Next Generation Computer that is right for you The NGC ("MAX") guiding computers (digital setting circles) each have a database of objects and various specialized functions.

    (NGC-superMAX with encoders and hardware) Complete Installation $699.00
    (NGC-MAX with encoders and hardware) Complete Installation $619.00
    (NGC-microMAX with encoders and hardware) Complete Installation $399.00

    SGT-MAX Computer (Software Guided Telescope) system:

    Create a real-time link with a PC using planetarium software. The interface can be accomplished with either the NGC-MAX or a BBOX and the appropriate interface cable and software. Please contact us or JMI for more information about the Software Guided Telescope

    Encoders and Hardware Only for a guiding computer:

    Encoders and Hardware set only $275.00

Pictures of the RB-66 Reverse Binocular

Click on a thumbnail picture to enlarge it.

The RB Family
The RB Family as of February 2005. Left to right: RB-66, RB-10, and the RB-16 Reverse Binocular Telescopes.
RB-66 Binocular
This RB-66 includes the optional handlebar and wheels for easy transport The final production version will have a modified handlebar that is attached to the end of the tripod leg rather than separate handles attached to the sides of the leg as shown in this picture.
RB-66 Binocular Handle
The handle, included with the handlebar and wheels option, inserts into one of the tripod legs.
The First Production RB-66
This RB-66 includes the optional handlebar and wheels for easy transport The final production version will have a modified handlebar that is attached to the end of the tripod leg rather than separate handles attached to the sides of the leg as shown in this picture.
The First Production RB-66
This RB-66 has the top cover removed so you can see inside the reverse binocular.
The RB-66 Prototype with the RB-66
The RB-66 includes the optional handlebar (not shown) and wheels for easy transport.
The RB-66 Prototype with the RB-66
The RB-66 prototype (left) is in the final phase of design/construction.
RB-66 Alignments
The RB-66 tubes must be aligned properly for comfortable viewing If the two images you see are not aligned, the first step is to align the images vertically using the horizontal adjustment Next, bring the two images together with the vertical adjustment If you try to do the two steps backwards, the eye will tend to merge the images automatically which will give you crossed eyes and cause eye strain



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