TeleVue "Starbeam" Sight

"The only red dot pointer worth owning"
Bruce Wrinkle, Senior Technician at Company Seven, more than 50 years experience observing.

Above: TeleVue 85 telescope with 2011 model Starbeam sight attached alongside.
This is atop one of our Universal Astronomics alt-azimuth mount heads (255,813 bytes).
Click on image to see enlarged view (608,460 bytes).

"Although the 9x, 5.5 degree true field capability allows Genesis (telescope) to operate as its own finder, I thought it would be nice to have a simple finder to point the telescope. The finder had to be elegant in form, function and operation and not have to be removed when storing the telescope. A unit-power finder serves these goals best. Choosing an "inverse-Herschelian" design for projecting a small "red star" seemed appropriate. With a 39mm "exit pupil" and unlimited eye-relief, I believe we met our goals. The proof? My wife now actually enjoys finding objects with it!" - Al Nagler.

In 1991 TeleVue announced a new product that was then, and remains to this day unique: the "Starbeam" sight. The "Starbeam" concept descends from "Heads Up Display" (HUD) research and development efforts that produced displays for aircraft and other devices. This is a zero power (no amplification) sight with a battery powered illuminator for use at night or at twilight.

An illuminator at the end of the sight nearest the observer projects an adjustable brightness red light emitting diode (L.E.D.) source through a pinhole to produce a red dot onto a precisely made concave optical beam-splitting mirror/lens. This is essentially a reversed "Herschelian" telescope in reverse. The crisply defined 10 arc minute diameter red dot appears to be about 1/3 the diameter of the moon. The transparent 39mm diameter beam-splitting mirror/lens has a precise compensating optical prescription with the front surface (R1) having a durable antireflection coating so that one can easily view through the window to sight an object in the distance while the red dot is projected onto it, while the sky appears normal and undistorted. To an observer looking down the axis of the sight towards the window from inches or some feet away, this red dot appears to be projected into the night sky at wherever the telescope is pointed.

Above: TeleVue Starbeam sight basic optical arrangement, viewed from its left side. This drawing shows the original style illuminator that was furnished with the Starbeam through 2010.

The brightness of the red dot can be adjusted at the illuminator with a simple to use dial so that faint objects in the sky are not obscured, and so that the observer's night vision is not adversely affected.

The system provides a 6 arc minute accuracy to make star hopping easy. The illuminator furnished has adjustable brightness control dial, and holds a common "button type" battery so that it requires no external power. Incidentally, the illuminator is made by Rigel Systems, a US company who makes this as a simpler version of their Pulseguide Illuminator for TeleVue.

RIGHT ANGLE VIEW MIRROR (year 2000 and later models)

Continuing the TeleVue tradition of seeking to improve that which already seems to have been perfected, for year 2000 TeleVue announced a refinement for the Starbeam sight aimed (no pun intended) at making the sight even easier to use. The Right Angle Mirror makes access to the observing position of the Starbeam sight more convenient by reflecting the star and red light images by about 90 degrees to a more comfortable viewing position. This improvement is note worthy for persons who are using telescopes where the installed sight location may put the eye position low to the ground (such as on smaller Dobsonian or on compact telescopes) and for those who find the head and neck position otherwise to be a strain or impossible to attain.

Above: TeleVue Starbeam optical arrangement with hardware, left side view showing Right Angle Mirror at rear flipped up for use (50,650 bytes).

The Right Angle Mirror is simply a flat mirror mounted onto a machined aluminum Illuminator support frame. The frame is pinned so that the mirror assembly may pivot to the front and rest in a stored position for those who do not need the mirror in place, or it may be pulled up and adjusted backward into a nominal viewing position.

Above: Current model TeleVue Starbeam Sight front left view, showing right angle view Mirror flipped up into use position (37,9017 bytes).

The Right Angle Mirror is retrofit able to older Starbeam sights. Please visit or contact Company Seven to order the hardware kit with installation instructions.

We offer three variations of the basic sight, only the mounting hardware varies:

1. Starbeam for TeleVue - bolts onto the Mounting Collar of TeleVue telescopes.

2. Starbeam for Newtonian - bolts onto the curved tube of larger telescopes.

3. Starbeam for SCT - provided with Quick Release Bracket and Dovetail. The bracket bolts onto the curved or flat surface.

Right: TeleVue Starbeam for SCT. Starbeam sight viewed from the front with Dovetail Plate attached and the Quick Rlease bracket shown at right (190,538 bytes)
Click on image to see enlarged view (84,767 bytes)

The Starbeam may be ordered in the Quick Release configuration shown above. This facilitates removal for transport, or the sharing of one Starbeam sight among several telescopes. The Dovetail Plate and Quick Release Base may be ordered separately. This can be retrofitted onto other Starbeam sights. The Quick Release Base incorporates a Stainless Steel cap screw which prevents the Starbeam sight from sliding back and off the telescope accidentally. If one prefers to slide the Starbeam back or forward on the Base then the screw may be removed to permit this.

MECHANICAL CONSTRUCTION

The Starbeam has a fully machined aluminum front cell, optical assembly support bar, and mounting bracket. The mirror/beamsplitting lens is permanently aligned to the front barrel, the illuminator assembly is aligned to the window. Unless subjected to gross abuse the Starbeam will provide years of service with no need for any other than cleaning of the window using common camera lens cleaning techniques. Its construction is extremely rugged to allow it to withstand all the handling that is typical of airline travel.

The concave beamsplitting mirror/lens is housed within a cylindrical housing that also functions as a dew shield/lens shade. Our optional heating element can be placed around this housing to keep dew or frost from forming throughout an observing session.

INSTALLATION AND OPERATION

The documentation provided with the Starbeam is comprehensive, and well illustrated. The basic installation procedure begins with selection of the correct mounting hardware. The Starbeam is furnished with either 1) the curved bottom Base Channel mounting bracket with a plastic spacer bar for optical tubes of more than 4 inch radius of curvature (mounting holes may have to be drilled), or 2) a flat bottom Base Channel for use with TeleVue telescopes or when the sight is to be installed onto a flat surface. This Base Channel is secured into place by one machine screw onto a telescope (contact Company Seven for compatibility advice). Company Seven sells spare Base Channels for those who wish to use a Starbeam on more than one telescope.

The Mounting Collar that is furnished on the recent and current production TeleVue astronomical telescopes is a two piece clamping bracket. TeleVue conveniently provides a slotted position with threaded holes at 10:30 and at 1:30 o'clock positions on the collar in order to accept the Starbeam Base Channel, and other options. If you own an older TeleVue 3 or larger telescope that does not have this collar, then we can provide a collar for you.

Above: TeleVue Starbeam sight basic mechanical arrangement, viewed from its left side (65,041 bytes).

Back out the Horizontal Adjustment screws until they clear the Optical Assembly Support Bar. While holding the Starbeam, back out the large diameter Lock Screw (on the Support Bar, towards the front of the sight) and lift the Starbeam from the Base Channel. Install the Base Channel with the end of the Base Channel that has the two Horizontal (Azimuth) Adjustment Screws facing away towards the front of the telescope (away from the observer). Once the bracket is secured, slip the Starbeam sight into the Base Channel. While holding the sight in place tighten both of the Horizontal Adjustment Screws into the holes at either side at the front of the Optical Assembly Bar to secure the sight. Then install the Lock Screw through the sight into the Base Channel. This completes attachment of the sight.

The Starbeam can now be adjusted up or down, and left to right with simple Horizontal and Vertical set screw mechanisms. The set screws have an easy to grip knurled head, no tools are necessary to align the sight. Now the sight is aligned to the main telescope. In the dark of night or twilight, point the telescope onto a very distant target (to avoid parallax). Turn on the illuminator of the Starbeam, and then adjust the sight up and down or left to right so that the red dot on its window points onto the target that the telescope is pointed to.

STARBEAM SPECIFICATIONS