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16" Reverse Binocular Telescope

"Sweet sixteen..." RB-16 Reverse Binocular (49,638 bytes).

Note: this is a preview of a new and exciting product which is now in prototype phase. Company Seven will receive the first production models and we will then update this review to include final dimensions, specifications, etc.

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.

Right: RB-16 Reverse Binocular prototype view from front right side. Note the red push button controls on handle, the secondary elliptical mirror in the OTA, and wheeled tripod mount (49,638 bytes). The RB-16 will be provided with an eight inch pneumatic wheeled "Alt-Az" or altitude-azimuth moving mount. However, the images on this page show the smaller wheel and carriage used with the RB-10 with the prototype RB-16. Click on image to see enlarged view (94,977 bytes).

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-16 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-16 consists of two 16 inch (406 mm) aperture f/4.8 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. 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 weight.

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 standard thin lightweight Primary Mirror of the RB-16* 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 and made with a thin 1-1/2 inch (38 mm) profile the primary mirror pair adds about 48 lbs / 21.8 kg to the frame of the RB-16. 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. The mirrors are ground and polished to a nominal figure, and then coated by a well regarded American fabricator. Most amateurs have been quite pleased with the performance of the mirrors sourced from this manufacturer for JMI.

* In addition to the choice of the standard mirrors mentioned above, Company Seven will make available to those buying their RB-16 from us the choice of a premium mirror pair. These optics are made to virtually any practical standard of excellence you decide, and low expansion materials including Quartz, Zerodur®, or ULE. Company Seven does not routinely become involved in providing mirrors for the amateur market, but so many people who seek such a high tech product as the RB-16 have asked for better mirrors that we have decided to offer to them the choice of an upgrade. Please contact Company Seven to obtain current pricing.

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 6 inch RB-66 may show objects about 335X fainter than the unaided eye, while each optical tube of the RB-10 (with similar physical length) provides about 900X the light gathering power over the unaided human eye. Now consider 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-16 Reverse Binocular Telescope RB-16 Reverse Binocular (55,770 bytes).

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, with the introduction of the 6 inch f/5 RB-66 in the Spring of 2003 JMI became the first manufacturer in the world to make the concept practical, and transportable for the enthusiast.

Left: JMI Model RB-16 Reverse Binocular Telescope model at the observing position optional (55,770 bytes).
Note the open truss, and just below is the integral wheeled stand.
Click on image to see an enlarged view (143,597 bytes).

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. The RB systems consist of two precisely joined Newtonian telescope optical tube assemblies, installed onto an alt-az mount creating a surprisingly compact and comfortable viewing experience. The available models manufactured by JMI are 6" RB-66, 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.

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. The rigid frame of the production models are manufactured from bar stock which is 1-1/2 x 3/4 inch (38 x 19 mm), with a 1/8th inch (2.3 mm) wall thickness. A light and dew baffling shroud is provided with the RB-16. This shroud will snap closed to cover the open truss area between the Nose Assembly of the telescope and the Primary Mirror cage.

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-10, easily managed and transported. The RB-16 weighs in at about 200 lbs. and so this is a system that must be wheeled to where it is to be used. The RB-16 is designed to facilitate quick take down and transport and rolling up into a van or SUV; a pickup can be used if it has a "passenger oriented" suspension.

What is an Alt-Az Mount?

The RB-16 Reverse Binocular is provided with an 8 inch pneumatic wheeled "Alt-Az" or altitude-azimuth moving mount the images on this page show the smaller wheel and carriage used with the RB-10 with the prototype RB-16. 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-16 Standard Features:

  • Two JMI Model RCF-2, 2 inch Motorized Focusers. A Reverse Crayford design for smooth and easy precise focusing
  • Motorized optical alignment of the optical tubes with the push of a button
  • Two 25mm eyepieces providing a .6 degree actual field of view - a stunning close up of the Moon, Orion Nebula, etc.*
  • "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-16 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 0.8 degree true field of view, tack sharp images across the entire field of view even when used of relatively "fast" telescopes as the RB-16, and good observing comfort. In time it may be possible to provide an accessory to permit use of very wide angle, lower magnifications 2 inch eyepieces - these could provide actual fields of view of well over one degree.

Customer Comments

"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-10 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-10 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)

"Leaves me feeling weak at the knees, and misty eyed" (Typical remarks at star parties where we at Company Seven have brought an RB system)

Optical Arrangement Parallel Newtonian Reflector
Aperture 16 inch / 406 mm
Focal Length 76.8 inch / 1950 mm
Focal Ratio f/4.8
Standard Primary Mirror Substrate Pyrex® 7740, Fine Annealed
Optional Primary Mirror Substrate Fused Silica, Zerodur®, ULE
Primary Mirror Thickness 2 Inch
Primary Mirror Weight (each) 24 lbs. / 10.9 kg
Standard Mirror Coatings Aluminized with protective overcoating
Cumulative Light Throughput (each OTA) Approx. 2,600X the light gathering power of the dark adapted, unaided human eye

Optical Tube Spacing 10 inch / 250 mm
Interpupilary Spacing Variable from 2 to 3.25 inch / 51 to 82 mm
Interpupilary Spacing Mechanism Variable, motorized
Focuser 2 inch Dia. / 50mm
Focusing Mechanism Variable speed, motorized
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 Portable Pier, 8 inch wheels
Bearings Derlin
Binocular Tube Assembly Length 60 inch / 152 cm
Binocular Tube Assembly Width 46 inch / 117 cm
Binocular & Stand Weight Appx. 175 lbs. / 79.5 kg

* Specifications are from prototype model, and are subject to change. 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-16 Optional Accessories
* Prices are based on work with prototype model, and are subject to change.

    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-10 and RB-16 Reverse Binocular

Click on a thumbnail picture to enlarge it.

The RB-16
The RB-16 Reverse Binocular, view from left side. Second prototype in February 2005.
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-10 Binocular
This RB-10 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-10 Binocular Handle
The handle, included with the handlebar and wheels option, inserts into one of the tripod legs.
The First Production RB-10
This RB-10 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-10
This RB-10 has the top cover removed so you can see inside the reverse binocular.
The RB-10 Prototype with the RB-66
The RB-10 includes the optional handlebar (not shown) and wheels for easy transport.
The RB-10 Prototype with the RB-66
The RB-10 prototype (left) is in the final phase of design/construction.
RB-10 Alignments
The RB-10 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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