TV 76 and TV Pronto

New Arrival: The TeleVue-76 APO Refractor
Aaron McNeely



The TeleVue-76

Honey, I Need a New Scope

I became interested in small refractors after observing with a TeleVue-85 at the 2000 Riverside Telescope Maker's Conference. I was really struck by the beauty of the views in the refractor. The stars formed delicate pinpoints, and deep sky objects were much more impressive than I would have imagined in such a small scope. I quickly decided to get a TeleVue scope, and I found a Pronto for a good price. Along with the scope, I purchased a TeleVue Tele-Pod, a small alt-azimuth mount that is ideal for small refractors.

I have owned my TeleVue Pronto since 2001. It has been a delightful telescope. I have used the Pronto more than any other scope that I have owned. The scope is easy to setup and provides impressive views. It is able to show a great range of phenomena, from low power Milky Way star fields to high magnification views of planets. The Pronto will easily locate the Messier and brighter NGC objects.

Being a semi-APO, my Pronto does exhibit some false color. At low powers, the scope is essentially color-free. The chromatic aberration becomes noticeable around 69x. For example, the moon in the Pronto exhibits a dull, purple rim along its bright edge. The most brilliant stars display subtle, purple disks, and, with 120x, white stars begin to take on a faint green tint that makes estimation of star colors more of an abstract enterprise. I became especially annoyed with this later characteristic. I wanted stars to appear natural even at higher powers.

TeleVue-76 and Tele-Pod


My Pronto and the TeleVue-76

Despite my enjoyment of the Pronto, I began more and more to want an APO. The TeleVue-76 and 85 scopes became increasingly attractive. Eventually I resolved to get one, and I saved money and purchased a TeleVue-76.

The TeleVue-76 is nearly the twin of my Pronto in appearance. Both have the same white, crinkle-finished tubes and black-anodized hardware, captive dew shields, and the legendary smooth TeleVue focuser. Both scopes employ black aluminum TeleVue clamshells and balance aids, and they both attach to the Tele-Pod with two stout 1/4-20 bolts and hand nuts.

My Pronto features a 70mm objective. The TeleVue-76 uses the same diameter cell as the Pronto's, yet is fitted with a larger 76mm objective. I can use the same full-aperture solar filter with the 76 that I use with the Pronto. Both scopes also feature the same bulletproof aluminum dust covers that thread into the objective cells.

TeleVue-76 (left) and Pronto objectives


The scope's Operating Guide says the following about the TeleVue-76: "This 3-inch aperture telescope has an 480mm focal length, f/6.3 APO doublet diffraction-limited objective." The lenses are also "fully multi-coated." The scope's resolution equals "1.5 arc-sec (Dawes Limit for a 3-inch aperture)." The magnification range equals "9x to 200x using TeleVue eyepieces." Sounds good.

The crinkle-white aluminum tube of the TeleVue-76 is actually a bit shorter than the Pronto due to the 76's compression ring fixture for holding the diagonal. My older Pronto employs a single setscrew within a smaller aluminum ring that covers the end of the focuser's chrome drawtube. The TeleVue-76's tube length had to be shortened to compensate for the increased length of the compression ring fixture.

TeleVue-76 (top) and Pronto OTAs


The scope's 1.25-inch adapter also features a compression ring. These devices are a significant upgrade in my opinion. In use, they have a nice feel and are much more secure than a single setscrew. The compression rings also tend to center the eyepiece within the drawtube rather than push it from one direction.

Both the TeleVue-76 and Pronto have 480mm focal lengths that provide the same set of magnifications. I imagine that Al did this to encourage Pronto owners to upgrade their scopes. I guess it worked.

One of the strengths of small refractors is the amazing wide field that these scopes can provide. For example, the TeleVue-76 with my 35mm Panoptic yields a magnification of 14x and a 5-degree field. This is the same diameter as ten full moons. This eyepiece in the 76 will display the entire Belt of Orion in one view. Essentially, this scope has the low power capability of binoculars, yet one can also zoom in and observe planets at high magnifications. It is no wonder why small APOs are so popular.

This graph shows all the major units of magnification produced by eyepieces between 2mm and 35mm in focal length. Both scopes have a focal length of 480mm. Traditionally, scopes perform best at magnifications below 50 times the aperture in inches. For the TeleVue-76, this equals 150x.


Spirit of 76

I obtained my TeleVue-76 in mid-December. Amazingly, I was able to take advantage of some clear weather on the night I received the scope. After placing the 76 on my Tele-Pod, I had a first light view of Deneb high in the west. The star looked pure white and sparkly at 15x with a TeleVue 32mm Plossl. I then switched to 69x with a 7mm Nagler. The defocused star appeared as a set of perfectly concentric rings. Very nice! In focus, the star also appeared natural in color at 120x with a 4mm Radian.

Racking the focus, I noticed a faint green tint on the defocused star outside of focus, and a faint purple tint inside of focus. When focused, the colors disappeared. I also observed that the rings of defocused light were more apparent inside of focus than outside, but the edges of both circles appeared identical. I did suspect a hint of purple around the edge of the Deneb at 120x. This was to be expected, and it is known that the TeleVue APO doublets display minor false color around the brightest objects at higher powers. I must emphasize that this tiny amount of false color was nowhere near as obtrusive as that presented by my older TeleVue Pronto.

I placed the scope on a CG5 equatorial mount to observe Mars. I examined the planet at 69x and 120x. Mars, over a month past opposition, displayed a nice set of markings that resembled a distorted Y that encompassed most of the planet's visible hemisphere. After consulting Mars Profiler at the Sky & Telescope website, I was able to identify these markings as Syrtis Major and surrounding areas. Despite some mediocre seeing, the views were free of false color, sharp, and full of detail at all magnifications.

Thus far the views and the star test looked great! I was very excited at the TeleVue-76's performance on Mars. I wished that Jupiter and Saturn were visible.

On the very next evening, I had a clear, sunset sky featuring Venus and the waxing crescent moon. I set up the TeleVue-76 on my Tele-Pod. In the scope, Venus appeared as a white crescent with a slight purple edge at 69x and 120x. Interestingly, the planet's crescent phase was a near twin of that evening's moon.

In my Pronto, Venus appears crisp, but displays a greenish tint and an obvious purple halo. The view through the TeleVue-76 is more pleasing due to its natural appearance.

Next, I examined the moon. In the TeleVue-76, the lunar terminator displayed crisp detail. Its bright limb was absolutely color free, even at 120x! I then switched to a 20mm TeleVue Plossl and enjoyed an absolutely lovely view of the entire moon in one field.

The low power Pronto views of the moon are nearly as exquisite as those in the TeleVue-76, but the old scope doesn't hold up as well under higher magnifications. For example, at 120x the moon in the Pronto displays a faint, greenish tint and purple haze along the bright limb. Crisp detail is still evident at this magnification, but the view in the TeleVue-76 is much more appealing.

Two nights later I was able to do more observing. The night was very clear, but cold. The temperature was near zero. I left the TeleVue-76 outside for a while to acclimate to the outside temperature.

When I got outside, Venus was already behind some trees. I sighted Vega instead. The brilliant gem shone a pure bluish-white color. At 69x and 120x, I noticed a slight purple rim around the star. Otherwise, the view was wonderful.

I observed a few double stars such as Albireo and the Double-Double. Albireo was crisp and gorgeous at low power. The TeleVue-76 easily split the Double-Double at 69x. My Pronto can also do this.

With a 9mm Nagler eyepiece, the TeleVue-76 resolved Polaris at 53x. The secondary appeared as a tiny faint blue companion hovering near the brilliantly illuminated whitish-yellow primary. At 18 arc seconds of separation, there was a sizable gap between the components. This was the most beautiful view of Polaris that I have ever had.

Next I split Zeta Aquarii, separation 2.1 arc seconds, into equal magnitude white disks at 178x which I obtained by combining my 7 mm Nagler with a TeleVue 2.5x Barlow. I also examined Gamma Ceti, a close double of 2.3 arc seconds separation that consists of magnitude 3.5 and 7.3 components. The dim secondary was affixed inside of the first diffraction ring of the yellowish primary. The whole system resembled a piece of jewelry.

My Pronto can also resolve the above stars, yet the natural star colors presented by the TeleVue-76 make the views much more enjoyable. All along, this had been a strong incentive for me to purchase an APO.

I also did some low power observing of star clusters. I used a 35mm Panoptic to observe the Pleiades and Double Cluster. Despite the first quarter moon, I had nice views of these objects. The Double Cluster in particular was quite impressive, and the view was filled with myriad tiny stars. In this regard, my Pronto and TeleVue-76 provide nearly similar views.

The first quarter moon was beautifully crisp and displayed absolutely no false color in the TeleVue-76. I noticed plenty of details. The terminator was just west of Mare Tranquilitatus. I spotted several wrinkle ridges and the tiny crater Linne. I also noticed the arcuate rim of Promontory Archerusia, it appeared as a string of dots which represented the shadows of individual mountain tips. I could discern albedo differences in the mare basalts. For example, I was able to tell the difference between the mare and the darker basalts that border it to the east and southeast. I also saw the Bessel ray that bisects the great mare. Just south of the mare, I noticed the linear Ariadaeus Rille.

Despite the small aperture of the TeleVue-76, an observer can see a great deal on the moon with this scope.

I decided to observe Mars again using the CG5 equatorial mount. The planet was a peach-tinted, slightly gibbous orb in the TeleVue-76. I observed using powers ranging from 69x to 178x. The best view was at 133x, which I obtained by inserting my 9 mm Nagler into a 2.5x TeleVue Barlow.

I noticed a four-pronged dark marking that crossed the globe of Mars. There were also two prominent bright patches interspersed between the dark features. Again, this was a view of the region around Syrtis Major.

Eventually, being a work night, I needed to go indoors. All in all, I had a beautiful night of winter astronomy. The scope was a joy to use.

A few nights later, just past full moon, I was able to use the scope again. We had just endured an unbroken run of cloudy nights.

Noticing that it was clear, I rushed outside with the TeleVue-76 and Tele-Pod mount. The 76's ease of setup facilitates such impromptu observing sessions.

Despite not being acclimated with the outside cold, the scope immediately was able to split Castor at 69x. The view was also decent at 120x. The stars resembled twin white disks, and I didn't notice any false color at both magnifications.

Next, I blasted my vision with the waning, nearly full moon. Again, no false color was evident, even at 120x. I particularly enjoyed the view at 15x in my 32 mm TeleVue Plossl. I was able to watch clouds rush through the field with the moon in the center staring down like the Eye of God.

I swept the scope back and forth a bit to assess how it handled scattered light. With the moon just out of sight, the scope's field of view was dark without any spurious reflections. With such control of unwanted light, one is able to observe stars right next to the moon's bright limb. This makes the scope ideal for observing the occultation of stars by the moon.

On the next afternoon, I was able to do some solar observing. I used the TeleVue-76 with an 1.25-inch Intes Herschel wedge for white-light views of the sun.

At 24x with a 20 mm TeleVue Plossl, the sun appeared as a white orb suspended in black space in the TeleVue-76. I also noticed granulation and limb darkening. The granulation resembled a delicate texture across the solar disk, and it seemed much more evident than in my Pronto. There were two decent sunspots that displayed dark umbral cores surrounded by fringelike penumbras. I obtained my best views of the sunspots using 9 mm and 7 mm Naglers (54x and 69x).

The solar views were absolutely pristine and displayed no false color. Even at 120x, I noticed no false color. This scope rocks!

My Pronto performs well on the sun, but the views in the TeleVue-76 were significantly better. The Pronto displays a lot of false color when observing the sun at higher magnifications. For example, the dark cores of sunspots are suffused with faint, purple light, and the sun's bright limb exhibits a purple rim.

Waiter, I would like my sunspots without purple cores please!

I haven't been able to do much deep sky observing due to lousy weather and the moon's phase. The scope should perform as well as my Pronto, which I have described in a previous Cloudy Nights review. And, of course, Jupiter and Saturn are coming soon.

You've made it to the end of my observing ramble. Let me emphasize that, despite being just a 3-inch scope, the TeleVue-76 does most types of observing very well. Yeah, the Lagoon Nebula won't look like a psychedelic trip as it does in a 17-inch reflector, but in a small refractor you can see it in the same field as the Trifid Nebula, which I think is pretty cool.


TeleVue-76 Solar Setup with 1.25-inch Intes Herschel Wedge


New and Improved

The TeleVue-76 functions as a new and improved version of the TeleVue Pronto. The mechanics of each scope are similar, yet the 76 provides high power views mostly free of false color, a feat unachievable by my Pronto. The TeleVue-76 can be used for a variety of observing, from low power star fields to crisp, high magnification views of the sun, moon, and planets.

Even though my Pronto is still a great scope, the TeleVue-76 is everything that I wished the Pronto had been. I've only had the 76 a short time, yet I predict that it will be my lifelong, heirloom quality companion. I really love the scope, and it is a lot of fun to own and use such a quality instrument.

Along with this new arrival, my wife and I are expecting twins any day now, hence the title of this article. I needed to write this article while I still have the time.


TeleVue-76 and SkyAtlas 2000