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Tele Vue Pronto and the "Living Star Atlas"



March 5, 2003

Why Buy a Small Aperture Refractor?

I have been an avid sky watcher since the late 1980's when I purchased an 8-inch Dobsonian reflector. I have used reflecting telescopes for many years, and I always assumed that big aperture was better when it came to telescopes. I changed my opinion after I spent a couple of hours observing with a Tele Vue-85 refractor at the 2000 Riverside Telescope Makers Conference. Mr. Nagler himself manned the scope, and I was impressed by the beautiful views through the 85. I quickly decided that I needed a small refractor. I eventually came across a Tele Vue Pronto at a good price, and, after persuading my wife to allow me to buy it, the rest is history.

My Tele Vue Pronto

My Pronto features a white crinkle-painted with black anodized fixtures. It includes a captive, sliding dew shield, a metal dust cover, and a beefy mount ring. The threaded dust cover screws into the objective lens cell for safe and secure protection of the scope's optics.

The smooth operating 2-inch focuser features oversized focusing and tension adjustment knobs. The focusing knobs are rubber edged aluminum and are machined to resemble the rims on a hot-rod automobile. The focuser will still turn even when the tension is completely tightened. This may seem less than ideal, yet the focuser securely holds heavy 2-inch eyepieces, even when the scope is pointed straight up.

The Pronto comes with a padded carrying bag for storage. The bag features a shoulder strap and could easily be carry-on luggage for astronomy vacations. The bag is also useful for cold-weather astronomy because it prevents the scope from dewing up when brought in from the outside.

I must admit my bias towards the Pronto. I really love this scope. It is a beautiful piece of work and a pleasure to use. The Pronto radiates quality and instills a pride of ownership. I feel as though I am enjoying the telescopic equivalent of a BMW or Ferrari.

Optics & False Color

According to Tele Vue's literature, the Pronto features a "diffraction limited, 70mm, E.D. objective." The scope has an aperture of 70 mm (2.8 in), a focal length of 480 mm, and a focal ratio equal to f/6.8.

This scope provides the utility of extremely low to moderately high magnifications. I generally use the Pronto with powers ranging from 14x with a 35-mm Panoptic to 120x with a 4-mm Radian.

The Pronto has some false color, but it is not intrusive until one uses higher magnifications. At low magnification, such as with a 32-mm Plossl, the views are essentially color free. A violet rim becomes apparent on bright objects as one climbs in power to 70x and higher. Also, a faint greenish tint can intrude upon white colored stars and is especially noticeable as one gets to powers over 100x. This greenish tint can make it challenging to determine the correct colors of high magnification double stars. This effect also seems to vary with seeing conditions and on some evenings it will disappear almost entirely. Red and orange colored stars remain unaffected by spurious color.

Star images are beautiful in the Pronto. The appearance of an out-of-focus star is nearly identical on either side of focus. The scope is perfectly collimated. At high magnifications, stars resemble perfect little bull's eyes. At low power, the stars are tiny pinpoints.

The Pronto is a nice compliment to a Cassegrain scope. It provides the wide fields that such scopes are unable to obtain. When using a star diagonal, the Pronto inverts images right to left just like a Cassegrain scope, so the star fields are directly comparable.

Pronto Accessories

I purchased my Pronto along with a Tele Vue Tele-Pod mount. The Tele-Pod is a simple altazimuth mount that works well with the Pronto. The scope attaches to the Tele-Pod cradle using two plastic wing nuts. I can adjust friction in the altitude axis by turning two brass knobs on the top of the mount. The Tele-Pod also features a padded handle similar to one on a photo tripod. To move the scope, I grasp the handle and sweep around. The motions are smooth and stable. The scope stays pointed where I want it.

The Pronto Balance Aid is an important accessory for this mount. It is a thick metal plate that connects the scope's clamshell mounting ring to the Tele-Pod head. The balance aid pushes the center of gravity of the scope forward so that the mounting ring may be positioned in the middle of the Pronto's tube.

Another useful balancing accessory is the brass Equalizer. This clever device is a heavy 1.25-inch eyepiece adapter machined from solid brass. The Equalizer provides more weight for the rear of the scope to help offset the heavy lens end.

The Pronto's mount ring features a "bat handle" that facilitates on-the-fly balance adjustments. Yet, when using the Pronto Balance Aid, brass Equalizer, and the tension adjustment knobs on the Tele-Pod mount, I never need to rebalance by moving the tube back and forth. The interplay of all of these variables produces the necessary amount of friction to keep the scope well balanced.

Observing with the Pronto

The Pronto is a wonderful general-purpose scope. This scope is so rugged and easy to use that you have no excuse for not observing. On the Tele-Pod, I can carry the entire set up with one hand. I use the scope for some time nearly every clear night that I am home.

The Pronto presents fine views of the planets, sun, and moon. The sun and moon are especially beautiful to observe. The Pronto also really shines on faint nebulas and open star clusters, and provides good views of all of the brighter Messier and NGC galaxies. Most globular star clusters appear as unresolved glows, yet the Pronto will resolve bright globulars such as M13 and M22. Double stars are pleasant to observe, despite the occasional false color that can seems to be related to atmospheric conditions.

I really like the rich-field capabilities of the Pronto. For example, with a 35 mm Panoptic at 14x, I am able to see the entire Belt of Orion in one eyepiece field. I often use the Pronto to explore an entire constellation by sweeping around with the scope. At such low powers you approach a magnification similar to that of binoculars, yet retain the stability and control of a mounted telescope.

When observing at such ultra low power views, I often feel as though a page from my star atlas has been transformed into a living star field right before my eyes. Instead of abstract symbols on a page, I am seeing miniature versions of real live objects set in large star fields. This "living star atlas" effect is really beautiful and unique to short focal length refractors such as the Pronto.

Summary

After using reflecting telescopes for many years, I came to appreciate refractors after observing with a Tele Vue-85 and purchasing a Tele Vue Pronto. The Pronto is a wonderful small refractor that is rugged and very well made. The scope is very easy to set up and operate, especially when combined with Tele Vue mounts such as the Tele-Pod. The Pronto is able to reveal all of the major phenomena of the solar system and sidereal universe. The wide-field views are especially enjoyable and provide a "living star atlas" effect. The Pronto has quickly become my favorite telescope, and I highly recommend it to beginning or experienced astronomers.

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