Above: TeleVue "Pronto" telescope with Lens Shade retracted, with 2 inch Mirror Diagonal attached,
in its Carrying Case (some optional oculars shown in case).
- The "Pronto" is among the least costly, good quality telescopes that is equipped with a 2" diameter focuser. So a person who is interested in photography, or exploring the new hobby of astronomy, or one who already owns a larger telescope will be able to employ suitable accessories. In fact almost every accessory made for the "Pronto" is compatible with larger telescopes - up to observatory class instruments use the same 2" and 1.25" accessories! There is no obsoleting of accessories, and one can use the very finest of a wide selection of eyepiece (oculars), 48mm filters, 2" camera adapters etc.
- The "Pronto" is extraordinarily versatile; astronomy, birding, panoramic observing, photography and more are within its grasp.
- For astronomy not only can it be used as a good primary telescope, but if the "aperture fever" bug bites and you find yourself wishing to see more with a larger telescope, then you are likely to keep the "Pronto" for use as a quick set up, second telescope to share with a crowd, or employ it onto a larger telescope as a first rate finderscope, or photo-guide telescope.
However, Martin Cohen of Company Seven, and others pressed Al Nagler of TeleVue to develop the idea into about 80mm (or a bit larger) f7 well corrected Apochromatic compact telescope, with a 2" focuser. This would be more suitable for observing the faint deep sky objects (at least the "Messier Catalog"), and the planets, while also retaining good portability. Well, Al Nagler listened and in June 1998 he responded by introducing the 85mm telescope!
Left: TeleVue 85mm telescope with optional Panoramic Mount, and smaller 70mm Pronto with optional Telepod Mount.
The objective lens of the "Pronto" is an air spaced doublet design where two lenses are matched to work as one. The front element is a positive fluorocrown substitute of Extra-Low Dispersion ("ED") glass; the rear element is of high index flint. Each lens spherical surface is smoothly polished, and in another testament to Al Nagler's forward thinking - this design can be made well, consistently. This design allows good color correction and stars appear to snap into focus as intense diamonds against a black velour background - the typical high quality refractor experience! But at high magnifications some false violet may be noticed on very bright small objects (stars including Vega, the planet Venus for example) - but these objects are pretty harsh tests of any telescope. Images of birds and planets are presented showing good detail, and daytime objects viewed at commonly used magnifications will appear quite three dimensional, free of apparent false color, sharp and contrasty.
The current production objective's four air to glass surfaces have anti-reflection coatings providing an overall light transmission greater than 94% in the visual wavelengths. So the system has about 93 times the light gathering power of the unaided human eye. On most nights, the settling down time for the lens is on the order of minutes, and even in sub-freezing conditions it rarely requires more than 15 minutes to acclimate.
While many owners are satisfied using the telescope at up to 200X or so, we believe the "Pronto" and it's cousin the "Ranger" are capable of operating at up to about 150X with optional lenses (any higher magnifications are not likely to show more detail), although some minor secondary color may become apparent to the trained eye at about 65X or higher. This telescope reaches that threshold necessary to clearly identify the major planets with several bands and their shades of color (beige, tan, browns) shown on Jupiter, the rings around and surface banding on Saturn, the polar cap on a fiery red Mars. With an eyepiece that shows 1/2 degree field or so, take a walk on our apparently three dimensional Moon! or follow its terminator throughout the moons phases (optional neutral density filter suggested to tone down its brightness). It will resolve objects on the moon as small as 6.4 km in diameter, it will see the four largest moons of Jupiter and their shadows cast on the surface when they transit past the planet!
With TeleVue's 2" focuser and a matched wide angle ocular the "Pronto" reveals its extraordinary wide field of view capability showing an area of up to 5.7 degrees (an area wider and taller than 11 full moons!) at 9X. With most small refractor telescopes, it's like trying to see the "Mona Lisa" through a straw...while "Pronto" shows the entire picture!
It can show most of the "Messier Catalog" of deep sky wonders, or can be employed for panoramic viewing of a seashore or countryside. Imagine a telescope that at a dark sky site has the combination of resolving power and field of view to sweep the Milky Way, show you the Double Cluster in Perseus (NGC-869), find the Andromeda galaxy (M-31), and see the form of large Nebulae such as the Veil and North American Nebulae! The TeleVue "Pronto" can reveal all three stars of Orion's belt. Closer in it reveals the jewel like stars of the Trapezium - a birthplace of stars, with a sweeping wisps of greenish gas clouds surrounding it.
The "Pronto" compares favorably against many telescopes in field of view:
- 1.9 at 22X for a common 80mm achromatic refractor,
- 1.4 at 31X for a common 6"f8 reflecting telescope,
- 2.1 degrees at 21X for an 5" Schmidt-Cassegrain (even when using an optional telecompressor lens)
- 1.3 degrees at 32X for an 3-1/2" Maksutov-Cassegrain.
In fairness, the cost the "Pronto" (equipped with either an optional Alt-Az or Equatorial mount) is positioned at a higher cost than several of the above telescopes. And as a practical matter for some applications in astronomy the nominal match of the "Pronto" telescope exit pupil to an average human eye will be obtained at magnifications of between 14X and 10X. While the best performance will be obtained at all magnifications if a wise choice of well corrected oculars is made; this goal is not attainable with several of the simpler eyepiece designs. Also consider that an optional good quality "Barlow" amplifying (negative) lens, or long eye relief TeleVue "Radian" ocular (introduced in 1999) will usually be put into use to attain the highest use able magnifications.
For film photography, the telescope (with our optional camera adapters) becomes a 480 f6.8 ED ultra telephoto lens, showing about 5.1 degrees across the diagonal of a 35mm camera film plane. And for CCD imaging operations the telescope at prime focus can show about one degree across the diagonal of a common 2/3" detector (such as that employed on some of our SBIG CCD systems. Optional techniques and hardware permit imaging of the planets, or of wildlife at much higher magnifications. The new TeleVue Field Flattener and the TeleVue 0.8X Focal Reducer (see options below) provide even sharper performance with film!
While the normal close focus distance is only 15 feet (4.6 meters), with optional 2" and 3" long x 2" diameter extension tubes then it becomes possible to observe at distances of as close as ten feet as a "long distance microscope".
The TeleVue "Pronto" can operate with a much lighter weight camera tripod, ideally with a well designed alt-azimuth head such as the TeleVue "Telepod" or with the wood "Panoramic" mount; such a design maintains the telescope well balanced throughout its travel to zenith, and this head has adjustable elevation ad azimuth clutches.
The "Pronto" has a fully machined aluminum front cell to house the objective lens and focuser housing. The objective lens is permanently aligned to the barrel as is the focuser assembly. Unless subjected to gross abuse this telescope will provide many lifetimes of service with no need for any other than cleaning of the front surface of the objective lens 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. However, some caution should be practiced not to damage the focuser pinion of any telescope; our experience with this focuser is that with routine handling this will not happen.
The "Pronto" incorporates a retracting dew shield/lens shade which is threaded for our optional filters. Also provided is a thread on lens cover of machined aluminum in a tube assembly that has an overall length of only 21-7/8 inches with its 2 inch diagonal attached. The precision TeleVue 2 inch focuser common to "Pronto", and the larger TeleVue telescopes is of a rack and pinion design with a tension/lock screw; this is one of the smoothest focusers made. The 1-1/2 inch diameter machined aluminum hand knobs resemble model car mag wheels whose hand grips are rubber covered to facilitate operation in all extremes; even when wearing gloves all the controls and focuser lock screw on this telescope are easy to manipulate. The set screw has an easy to grip knurled head, this permits one to adjust resistance of the focuser to its draw tube thereby compensating for heavy loads that might otherwise cause an unintended shift of focus. The lock screw that is in the draw tube ring at the proximal (to the operator) end of the draw tube adjusts tension to retain accessories such as the 2 inch diagonal, or a camera; this set screw is captive so it will not easily come out.
The mounting collar is a two piece bracket. On one side is an Allen head screw, on the other side is a tension adjustment knob. This design permits one to adjust the grip on the barrel so that the telescope may be easily moved back and forth to compensate for changes of accessory loads that may affect the balance of the telescope on a mount. The fabric lined mounting collar has three 1/4"-20 tpi threaded sockets in the base to facilitate mounting the telescope onto a variety of tripods and mounts. At the 10:30 and 1: 30 o'clock positions on the top of the collar there is a dovetail platform to accommodate a variety of options including the "Starbeam" sight, or a "Piggycam" piggyback photography mount.
The telescope focuser is furnished with a reducer to permit the use of 1.25 inch diameter accessories. A lock screw with a knurled head that is at the proximal end of the female 2 inch barrel (nearest to the operator) to retain accessories such as the 2 to 1.25 inch reducer, 2 inch diagonal, or photo adapters; this set screw is captive and so it will not easily come out.
The customer can order the "Pronto" with a choice of either of the following included with the telescope (an Image Erecting Prism is available as an option only):
- TeleVue 2 inch Diagonal: 90 degree 2 inch diameter precision mirror diagonal (1/10th wave quoted) which has an enhanced aluminum reflective coating. The male 2 inch barrel is threaded to accept 48mm photo and visual filters. The interior is fully anti reflection coated and ribbed. This diagonal permits an observer to employ a wide selection of 2 inch diameter oculars or 1.25 inch items with reducer in place. The 2 inch diagonal configuration necessitates the use of an included "Pronto Balance Adapter Plate"; this is attached to the telescope mounting collar and will offset the telescope on the Panoramic to attain proper balance.
- TeleVue "Everbrite" Diagonal: 90 degree 2 inch diameter precision mirror diagonal which appears similar to the above listed diagonal but which has a more highly reflective and very durable E-Beam reflective coating. This configuration also includes a "Pronto Balance Adapter Plate".
- TeleVue 1.25" Diagonal: 90 degree 1.25 inch diameter precision mirror diagonal (1/8th wave quoted) which has has an enhanced aluminum reflective coating. This is a good choice for those who either seek the most economical or light weight configuration of the telescope, or who do not require a wider field of view than the 3.6 degrees at 12X provided by the lowest magnification 1.25" oculars. This may also be the best choice for those who already own a 2" Mirror Diagonal on a larger telescope and want to keep the acquisition cost lower, assuming you do not intend to use both telescopes simpultaneously.
NOTE: the view when using the telescope with either the 2 inch or 1.25 inch mirror diagonals will appear to be right side up, and is reversed left to right. This is not usually a problem for astronomy or nature observing because the image quality and field of view provided by the high quality mirror with 2 inch diameters panoramic oculars is exceptional. And so while we do offer optional 45 degree inclined image erecting prisms, these prisms can only accommodate 1.25" oculars. Furthermore, the erecting prisms will not provide image quality to equal that of a mirror diagonal, this is particularly perceptible at higher magnifications. However, for low to medium magnification applications where one needs correct images (such as to read numbers, etc.) then the prism should be suitable.
The front lens cell, focuser housing, mounting collar, and diagonal are finished in a lustrous black satin anodizing. The barrel is powder coated in a mottled forest green color (as illustrated above) or powder coated in a neutral ivory finish, or in solid brass (with brass trim) if demand so justifies it. The optical tube assembly is finished internally with an anti-reflective method unique to the TeleVue telescopes.
The telescope is furnished with a dense polyester foam lined nylon carrying case with a zippered lid. This case has extra space to accommodate a selection of several 1.25 or 2 inch oculars, camera adapter, etc. And in a nice touch the case has a cutout provision for the "Starbeam" or "Qwick-Point" sights.
TELEVUE 70mm f6.8 TELESCOPE SPECIFICATIONS
* Specifications are subject to change without notice.
||Less than 0.03% focus variation from 706nm to
||1.64 arc seconds
||Fully Multi-coated. Overall transmission greater than 94% in
peak visual wavelengths
||9x to 140x
||Powder coat finish, 14.5" aluminum tube; fully baffled,
permanently aligned cell construction
||2 inch rack and pinion
|Tube assembly length:
||17.5" overall w/2" Diagonal
|Weight with diagonal:
||5 lbs. 16 oz.
|Carrying case type:
||Custom padded bag
|Case outside dimensions:
||20.5" x 9" x 6.5" (52cm x 23cm x 17cm)
||212 Line pairs/mm
|35mm prime-focus field:
||4.2 x 2.9 degrees @ f7
|35mm field with 2x Barlow:
||2.1 x 1.4 degrees @ f14
||TeleVue 20mm Plossl, 1.25 inch Dia.
The telescope is furnished with a TeleVue 20mm Plossl 1.25" ocular. Suggested options include either a 2X "Barlow" or TeleVue 2.5X "Powermate" lens, and some of these oculars:
- Panoramic Mount and Tripod: Cradles the telescope at its center of gravity for ideal balance at any viewing position. Vertical travel from -17 degrees (below horizon) up to +85 degrees, with full 360 degree rotation. Head is precisely machined of black anodized aluminum, with brass bearings and clutches on both axes. American ash wood tripod, two section extension design, with accessory tray/leg brace.
Pronto telescope shown with 1.25" Mirror diagonal on Ash wood Panoramic Mount.
The Panoramic Mount is also available with a Walnut finish wood tripod, and with brass tripod head and trim to match the brass "Pronto" and "85" telescopes.
- Telepod Head: Provides vertical travel from -17 degrees (below horizon) up to +85 degrees, with full 360 degree rotation. It is precisely machined of black anodized aluminum, with brass bearings and clutches on both axes. Can be attached to most camera tripods.
- Equalizer: A slip fit machined bronze, heavy 2 to 1.25 inch diameter reducer adapter. Helps to keep telescope balance when switching to and from light and heavy accessories and eyepieces. Particularly helpful when using telescope with Alt-Azimuth mounts.
- TeleVue 1.25" Image Erecting Prism Diagonal: 45 degree angled, 1.25 inch diameter precision image erecting prism diagonal with high transmission coating. This is a good choice for those who must have an image erect and correct left to right view (such as for reading print in the distance), and who do not intend to use the telescope at higher magnifications.
- "Starbeam" Finder: Beautifully machined and black anodized aluminum, on a quick release machined hardware. Battery powered illuminator is adjustable in brightness; it projects a 10 arc minute diameter red dot onto a transparent 40mm clear aperture window so that the dot appears to be over wherever the scope is pointed. Six arc minute accuracy make "star hopping" easy.
- Eyepieces: Plossl, Orthoscopic, traditional Erfle and wide angle eyepieces show sharp images only in the center of the field when employed with telescopes such as this. These are acceptable as long as you realize this limitation, and find this unobtrusive. If you object to less than perfect images at the edge of the field, then Company Seven recommends the TeleVue "Nagler", "Radian", or "Panoptic" eyepieces. These oculars have the best flat field images and will bring out the most in your "Pronto" (and many other) telescope. A 35mm to 55mm focal length eyepiece can also make the main telescope also serve as your finder. Please refer to the brochure and the test report/data generated by Company Seven enclosed with our telescopes for descriptions of these items and additional accessories.
- Barlow Lens: Company Seven suggests you consider any of a number of Barlow we offer to double or as much as triple the telescope magnification. Contact us for suggestions on how to to best meet your goals.
- Field Flattener: threads onto the male thread of the TeleVue telescope camera adapters. This makes the "Pronto" telescope perform as a 520mm f7.4 Flat Field telescope, with only very slight vignetting at the extreme corners of the film negative. Requires only an optional "T-Adapter" ring for Nikon, Minolta, etc.
- Focal Reducer 0.8X: threads onto the male thread of the TeleVue telescope camera adapters. This makes the "Pronto" telescope perform as a 384mm f5.5 Flat Field telescope, with only very slight vignetting at the extreme corners of the film negative. Requires only an optional "T-Adapter" ring for Nikon, Minolta, etc.
||Actual field of view
|12mm Nagler Type 4
Contents Copyright 1997-1999 Company Seven All Rights Reserved