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Above: TeleVue 102mm telescope optical tube assembly, lens shade retracted. Shown with optional TeleVue
2" Mirror Diagonal, Mounting Collar, and Losmandy Model GM-8 German Equatorial Mount (45,316 bytes).
Note: the textured finish of the Dewcap, Lens Cover, and Focuser, and lack of Rear Cell (Telecompressor and
From October 2000 to June 2001 the color of the Front Cell and Focuser were Evergreen, with black being
Introduced in the Summer of 2000, the "102" telescope is a variation derived from the fifth generation TeleVue "101" and "Renaissance" telescopes. The 101 systems are each a four element refractor design succeeding the original 5 inch "MPT" system introduced in 1982, the beautiful brass 4 inch aperture f5.5 "Renaissance" telescope introduced in 1984, the "Genesis" 4 inch f 5 telescope of 1988, and the "SDF" 4 inch f5.4 of 1993. Al Naglers patented four element design is based on the "Petzval" concept where a two element air spaced objective lens at the front of the telescope passes the light through to a second doublet lens positioned at the rear of the telescope and before the focuser. The rear doublet lens group functions include 1) reduce the effective focal length, and 2) reduce or eliminate curvature of field.
The 102 telescope is similar to the 101 series in that it employs the large air gap SD apochromatic doublet (two lens) objective for very good control of chromatic and spherical aberration. However, the 102 does not incorporate the second doublet lens (telecompressor - focal reducer, and field flattener element) as does the 101 series, and so the resulting effective focal length of 880mm is longer in the 102 telescope than it is in 101 (540mm focal length) series. Practically speaking this means that the 102 telescope has some advantages over the 101, and some disadvantages:
There is however, an optional Focal Length Reducer/Field Flattener designed for the 102. Introduced in November 2000 this accessory will provide an effective focal length of about 704mm at f6.9.
Company Seven applauds this decision on the part of TeleVue since we can now customize each 102 telescope to meet the needs of each particular observer without forcing them to pay for accessories such as those included with the other TeleVue telescopes which may be redundant or obsoleted by the customer's applications.
While at first glance the cost of the basic 102 telescope within several hundred dollars of the multipurpose TeleVue 85 telescope price, after considering the accessories one pays to complete the 102 to the level of the 101, then one pays about $250 less for the accessorized 102 than the 101. If however, one is moving up from a telescope such as the TeleVue 85 (assuming one has or will buy a suitable mount), or some other telescope which already is equipped with a premium quality 2" mirror diagonal, and eyepieces, then then only extra accessory needed will be the mounting hardware (TeleVue Collar, or third party mounting rings), and a mount. Many of our customers buying the 102 (and similar better telescopes) already own some of the accessories or a suitable mount for use on other telescopes, the 102 eliminates the requirement to duplicate some of these accessories.
The TeleVue "101" series telescopes introduced in 1998 are the first large TeleVue Apochromatic refractors which Company Seven found to be truly competitive in optical performance with the best 4 inch aperture Apos ever made; providing visually false color-free, sharp, clear and high contrast images. The TeleVue 101 remains the worlds fastest, flat field apochromatic 4 inch telescope - while the brass "Renaissance 101" also remains the world's most beautiful. The TeleVue 102 now means TeleVue has another scope, even better suited to those who seek uncompromised views of the brighter objects, and at a lower cost than most premium 4 inch Apochromats.
Above: TeleVue "102" telescope optical arrangement; 1. air spaced doublet objective, 2. 2" focuser, 3. 2" to 1.25" reducer (5,683 bytes)
The objective lens of the 102 is of an SD air spaced doublet design where two lenses (crown and flint) are matched to work as one; the positive element is of a fluorocrown substitute with special dispersion glass. In fact this design allows excellent color correction without annoying purple fringes (secondary color) common to less sophisticated achromatic refractors. And it will perform better than a number of older triplet and modern doublet apochromat designs. There will be a barely perceptible false color in this design, and what there is may be visible only to the more discriminating observers when using the telescope at very high magnifications well in excess 300x on some of the very brightest starts. Spherical correction is very good also with the air gap objective contributing to this correction. Images of the stars and the planets are presented in their natural colors, daytime objects viewed at commonly used magnifications will appear quite three dimensional, sharp and high in contrast.
The objective's four air to glass surfaces multi-layer anti-reflection coatings improve overall light transmission across the visual wavelengths and from 400nm to well beyond 700nm. Overall the complete system provides about 202 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: from room temperature to sub-freezing conditions it rarely requires more than 30 minutes to acclimate.
Company Seven's Q.C. testing of each telescope we receive has shown the lenses are well figured and the design so refined that the consistency between telescopes is quite good; each is capable of operating at very high magnification cleanly (even with optional "Barlow" or "Powermate" lenses). This telescope reaches the threshold necessary to routinely obtain meaningful views of the planets; showing several bands and their shades of color (beige, tan, browns) on Jupiter, observe the four largest moons of Jupiter and their shadows cast on the surface as distinct discs as they transit across the planet! Study the Cassini division and banding on Saturn, the polar cap and dark markings on a fiery red Mars. With an eyepiece that shows 1/2 degree field or so (such as an 8mm "Radian") take a walk on our apparently three dimensional Moon possibly resolving objects on the Moon as small as 4.4 km in diameter. Or follow its' terminator throughout the moon phases (optional neutral density filters suggested to attenuate the brightness). With an optional white light solar filter (such as our Baader AstroSolar film) one may view Faculae and Sunspots on the Sun! With optional Hydrogen Alpha filters (such as our DayStar ATM or University series) observe Faculae, Sunspots, the Peach-fuzz like photosphere on the Sun as well as the sheer curtain like Prominences as they erupt from the Sun out into the blackness of space!
Above: TeleVue 102mm telescope 2" Focuser (with optional diagonal) in Evergreen finish (54,505 bytes).
With TeleVue's 2" focuser and a matched wide angle ocular the 102 reveals its very good wide field of view ability showing up to 3 degrees at 16X to reveal the entire Messier Catalog of deep sky wonders, or to 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, see the Double Cluster in Perseus (NGC-869), find the Andromeda galaxy (M-31) and see it's ellipsoid shape, and with no doubt see the distinct forms of large Nebulae such as the Veil and North American Nebulae! With a wide angle eyepiece the TeleVue 102 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. With a higher magnification M13 (the Hercules star cluster) takes on a three dimensional "salt and pepper" appearance even from suburban skies on a clear night. By the time one finds a large enough aperture Catadioptric, reflecting, or achromatic refractor to see similar detail, then one can only see a fraction of their area due to the relatively high focal length of these competing telescopes; with other telescopes it would be something like trying to observe the night sky through a straw!
In fact, one of the finest advertisements ever published for a telescope concept is the book Deep-Sky Companions: The Messier Objects where the author Stephen O'Meara sought to keep the drawings relevant to the amateur. To produce the highly detailed drawings of these celestial objects Stephen chose to observe with the second generation TeleVue "Genesis" telescope (4" aperture, 500mm f5) which has since been replaced by the improved 101 and 102 apochromatic telescopes. This book has become one of our best advertisements for the versatile, readily transportable fast 4 inch (10cm) refracting telescopes. Similarly to keep things simple, and relate as much as possible to the average amateur observer Stephen chose to use the telescope on the simple but sturdy TeleVue "Gibraltar" alt-azimuth mount with Ash Wood tripod. He equipped the telescope with only a modest selection of accessories: TeleVue 22mm "Panoptic" eyepiece (providing 23X, 2.85 Degrees Actual Field of View), a 7mm Nagler eyepiece (71X, 1.08 AFOV), and a TeleVue Barlow lens to increase the magnification by 1.8X.
The 3 degrees provided by the 102 compares favorably against many telescopes in field of view:
In fairness, the cost the TeleVue 102 (equipped with either an optional Alt-Az or Equatorial mount) is positioned at a higher cost than most of the above telescopes. And as a practical matter for some applications in astronomy the nominal match of the "102" exit pupil to an average dark adapted human eye will be obtained at magnifications of between 20X and 16X. The best performance will be obtained at all magnifications if a wise choice of good quality oculars is made however, since the 102 telescope incorporates a focal ratio of 8.6 then it is compatible with most of the simpler eyepiece designs. Again consider that an optional good quality "Barlow" or "TeleVue Powermate" amplifying (negative) lens, or optional long eye relief TeleVue "Radian" ocular (introduced in 1999) will usually be put into use to attain the highest use able magnifications which are necessary for observing small bright objects including planets, and double stars.
The TeleVue 102 can operate on any of a number of suitable optional German Equatorial or for extreme ease of use or portability consider our alt-azimuth mounts including:
Furthermore, this is a telescope one can grow with since most of the accessories that one would buy for this telescope are upwardly compatible with any larger telescope that one is likely to buy at Company Seven.
The 102mm 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 and in its hard shell case is routinely transportable.
The 102 telescope incorporates a retracting Dew Shield/Lens Shade. Also provided is a thread-on Lens Cover of machined aluminum in a tube assembly that has an overall length of only 33 inches with it's 2 inch diagonal attached. The precision TeleVue 2 inch focuser is a rack and pinion design with a tension/lock screw which helps to lock focus for uses including photography; this is one of the smoothest focusers made. The 1-1/2 inch diameter machined aluminum hand knobs resemble model car brushed aluminum mag wheels. The knob hand grips are rubber covered to facilitate operation in all extremes; even when wearing gloves all the controls on the 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 optional 1.25 or 2 inch diagonal, or a camera; this set screw is captive so it will not easily come out.
The objective (front) lens cell, focuser housing, and the optional mounting collar, and 2" Mirror Diagonal are anodized in a lustrous black satin. In addition, the lens cell, and focuser housing of the original telescopes were then covered in a durable black powder coat finish; this was changed to dark green in October 2000 with Black being available from Company Seven only by special order. The barrel too is powder coated in textured neutral Ivory (as illustrated above). The powder coat feels like a textured smooth plastic covering which is quite comfortable to manage even in extreme cold or damp climates. Since August 2001 TeleVue 102 telescopes are made in Ivory with Black cell and focuser as shown at the top of this article. While a Brass version ("Renaissance 102") is available too. The interior of the optical tube assembly is lined with an anti-reflective covering unique to TeleVue telescopes, which is then finished with anti reflective black paint.
Included with the telescope is a die cut, foam lined hard shell carrying case with latch closures. This case is 38-1/2 x 10-1/2 x 9-1/2 inches in dimension, and it has extra space to accommodate several 1.25 or 2 inch oculars, camera adapter, etc. And in a nice touch the case has a cutout provision for the optional Starbeam or Rigel QuikFinder sights. The case will fit into the overhead storage area of most commercial aircraft (one exception being the L-1011). However, many airlines do not permit such "oversize" packages on board; even if they do you will not be too popular with other passengers so you might ask a Flight Attendant to store the telescope for you - possibly in the garment bag storage area.
The telescope, in it's case is well padded and then packaged for delivery within one box, and then this is placed into another box. We suggest that telescopes such as this be sent by a priority air service (FedEx, UPS, U.S. Mail, etc.) to reduce risks of loss or damage in shipment. If you intend to ship the telescope regularly, or check in the telescope on airplanes then you should consider buying a Company Seven Airline Transport Assoc. Appoved transport/shipping case.
|Clear aperture:||101.95mm (4")|
|Focal length:||880mm (34.6")|
|Resolution (visual):||1.15 arc seconds|
|Resolution (photo):||260 line pairs per mm|
|Magnification range:||16x to 360x|
|Tube assembly:||Powder coat finish, aluminum tube; fully baffled, permanently aligned cell construction|
|Focuser type:||2 inch rack and pinion|
|Focuser Travel:||2-3/8 inches|
|Telescope length with diagonal:||78.7cm (31") dew cap retracted|
|Weight with diagonal:||10 lbs. (4.5 kg)|
|Weight in carrying case:||19 lbs. (8.6 kg)|
|Shipping Weight:||29 lbs. (13.2 kg)|
|Shipping Dimensions:||40 x 13 x 10 inches|
|35mm prime-focus field:||2.28 x 1.6 x 2.8 degrees @ f8.7|
|35mm field with Focal Reducer:||2.9 x 2 x 3.5 degrees @ f6.9|
|35mm field with 2x Barlow:||1.1 x 0.8 x 1.4 degrees @ f17.4|
Every U.S. registered buyer of this new telescope will receive The Next Step - Finding and Viewing Messier's Objects! A copy autographed by the author Ken Graun will be mailed by TeleVue to any U.S. customer who buys and registers any TeleVue telescope after 15 September 2005 at no cost.
This is a convenient astronomy guide book written for those who may be newer to the hobby, or who appreciate a more fun approach to reading. This book is an interesting read for those who appreciate the historical insights to the life of Charles Messier (b. 26 June 1730 in Lorraine France, d. 12 April 1817 in Paris), the French astronomer who gave us the Messier Objects catalog of celestial wonders. The author performed extensive research in the USA and overseas to accumulate the knowledge that he conveys in a very readable format. A delightfully illustrated handy book with some beautiful color pictures, color illustrations and charts, and with black and white photo plates of the Messier Objects. The book features photos with visual descriptions by the author with a TeleVue 101 4 Inch f/5.4 and TeleVue 102 4 inch f/8.6 apochromat refracting telescopes.
Company Seven recommends this to those who wish to read an introduction to using amateur telescopes and learn how to use them to star hop or navigate into these first hundred or so deep sky objects. It is well illustrated, good and entertaining reading, and suitable for most children at Junior High/Middle School levels up to adults.
Please refer to our TeleVue News article of 15 September 2005 for more information about this free Ken Graun book promotion.
Right: TeleVue Ash Gibraltar Mount with optional telescope, Starbeam Sight, Eyepieces and SkyTour CPU on Accessory Tray.
The mount head is made of fully machined of aluminum which is black anodized, with brass elevation bearings and azimuth nylon bearing providing smooth vertical travel from 10 degrees below the horizon up to 85 degrees overhead, and smooth full 360 degree rotation. Clutches on the elevation axis permits the operate to compensate for changing accessory loads, or with the Azimuth control to lock the telescope in place. The tripod is made of American ash, in a two section extension design providing a range of 3 feet up to 5 feet, with accessory tray/leg brace. The "Gibraltar" mount solved a problem of ease of use for those who are frustrated by the weight and relative complexity of equatorial mounts, and it provides a mount far better suited to terrestrial applications than an equatorial mount or common camera tripod would be. These mounts remain available with either a beautiful ash tripod in natural finish (Yes, ash is the hard wood used to make baseball bats)with black trim, or a in solid walnut. Since it's introduction the "Gibraltar" head has been engineered to accept optional encoders to feed a "Digital Setting Circle" CPU such as that offered by TeleVue and third party units; this helps one to navigate the sky and find objects that might be hard to find particularly from suburban settings.
Mounting Rings: sold by the pair, each is a hexagonal split ring hinged bracket used to attach the telescope onto one of a number of available German Equatorial mounts. On one side of each ring is a knurled hand knob (wrench not necessary) so that one may loosen the grip of the rings and then adjust the the optical tube assembly back or forth (on the felt lining) to balance of the telescope on a mount. At the top and bottom of each ring there is a platform with threaded holes to accommodate a variety of TeleVue and third party options. Mounting Rings are not compatible with the TeleVue Gibraltar mount and tripod system, nor will they readily fit into the provided telescope carrying case.
The "Everbrite" mirror was introduced in 1999, it features a very high-tech dielectric coating (developed originally for military optics used in hostile environments such as blowing desert sand) which provide optimum performance and years of use. This new TeleVue 2 inch diagonal has no aluminum or other reflective metal coating. Instead, the reflective surface consists of 52 layers of thin film oxides similar to those used in anti-reflection coatings. The coatings are deposited by an electron beam evaporator at a high temperature. The result is that reflectivity is above 99% over the entire 4000 to 7000 Å (Angstrom) photo-visual range. Thin film coatings have extremely low surface scatter compared to aluminum or enhanced aluminum coatings; examination with a laser source shows approximately a five fold improvement in surface scatter. The mirror diagonal provides a comfortable viewing position for the observer by diverting the image at the rear of the telescope off axis by 90 degrees to the side, with minimal degradation of image quality. The view when using the telescope as it is provided 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 provided by the high quality mirror and 2 inch diameters panoramic oculars is exceptional.
|Eyepiece||Magnification||Actual field of view||Exit pupil|
|55mm Plossl||16x||3.0 degrees||6.38mm|
|35mm Panoptic||25x||2.52 degrees||4.06mm|
|31mm Nagler Type 5||28x||2.71 degrees||3.59mm|
|27mm Panoptic||33x||1.99 degrees||3.13mm|
|22mm Nagler Type 4||40x||2.03 degrees||2.55mm|
|22mm Panoptic||40x||1.62 degrees||2.55mm|
|20mm Plossl||44x||1.11 degrees||2.32mm|
|17mm Nagler Type 4||52x||1.58 degrees||1.97mm|
|12mm Nagler Type 4||73x||1.11 degrees||1.39mm|
|9mm Nagler||98x||0.80 degrees||1.04mm|
|8mm Radian||110X||0.54 degrees||0.93mm|
|6mm Radian||147x||0.41 degrees||0.70mm|
|5mm Radian||176x||0.35 degrees||0.58mm|
|Eyepiece||Mag. w/2X 2 Inch Barlow||Actual field of view||Exit pupil|
|35mm Panoptic||50x||1.26 degrees||2.03mm|
|31mm Nagler Type 5||57x||1.36 degrees||1.80mm|
|27mm Panoptic||65x||0.99 degrees||1.56mm|
|22mm Nagler Type 4||80x||1.01 degrees||1.28mm|
|22mm Panoptic||80x||0.81 degrees||1.28mm|
|20mm Plossl||88x||0.56 degrees||1.16mm|
|17mm Nagler Type 4||104x||0.79 degrees||0.99mm|
|12mm Nagler Type 4||147x||0.56 degrees||0.70mm|
|9mm Nagler||196x||0.40 degrees||0.52mm|
|8mm Radian||220X||0.27 degrees||0.46mm|
|6mm Radian||293x||0.21 degrees||0.35mm|
|5mm Radian||352x||0.17 degrees||0.29mm|
* The telescope is capable of operating at magnifications greater than listed in this briefing above.
Contact Company Seven for additional advice about outfitting the NP102 for high magnification observing.
Above: Company Seven ATA Case custom fitted for a TeleVue NP101 telescope and accessories (138,840 bytes).
Click on image to see enlarged view (240,578 bytes).
Please contact Company Seven for additional information and pricing.