Questar Maksutov-Cassegrains

More Information  · Supplied Accessories  · Recommended Accessories Price $6,995.00 Highest Useful Magnification 162x Visual Limiting Magnitude 12.2 Focal Length 1300mm Focal Ratio f/14.6 Resolution 1.3 arc seconds Aperture 3.5" Weight 7 lbs. Heaviest Single Component 7 lbs. Warranty 5 years

Maintaining the extraordinarily high visual and mechanical standards for which Questar has always been justly famous, these telescopes are hand-crafted and have documentation reflecting the manufacture and optical performance of each individual telescope. A limited edition 50th Anniversary Model Questar will be a treasure for decades to come.

The Standard Questar 3.5" (on which the 50th Anniversary Edition is based) has long been regarded as the finest personal telescope in the world. In addition to its legendary resolution, flatness of field, contrast, and 1/8th wave accuracy through the system optics, the Standard Questar has a suite of standard integrated features that are simply unavailable as a package on any other telescope, some features that are costly options on other telescopes – and some features that are unavailable on other telescopes, period!

For example, at a distance of one mile, optical theory prescribes a resolution of 1/3rd of an inch for the 3.5" aperture Questar – but a 3.5" Questar like this 50th Anniversary Edition, under good seeing conditions, can routinely resolve much thinner bicycle spokes at one mile, and leaf stems at two miles! And theory says that a Questar should not be able to resolve lunar craterlets and rilles under 1.3 arc seconds across – yet there are countless Questar owners and Questar photos that prove optical theory wrong.

What is it about a Questar that lets it exceed the theoretical limits on a day in/day out basis?

Simply this: a fanatical devotion to hand-crafted accuracy.

Each optical element in a standard Questar typically tests out at a truly outstanding 1/50th wave accuracy (shaped to within four ten-millionths of an inch of perfection!) This produces guaranteed total system performance at the Cassegrain focus of 1/8th wave or better. That’s twice the accuracy needed to meet Lord Rayleigh’s Criterion, which specifies the level of optical excellence required to yield visual performance that’s indistinguishable from perfect optics. But this 50th Anniversary Edition does even better than a standard Questar. The 50th Anniversary Edition has guaranteed 1/10th wave optics at the Cassegrain focus!

Most commercial telescopes claim to be “diffraction-limited" (which is generally assumed to mean 1/4th wave accuracy). However, they do not specify whether that is for individual components or the system as a whole. In either case, it’s a far cry from the 1/10th wave total system accuracy at the eyepiece of this special Questar.

This significant difference in total system accuracy is one reason why a 3.5" Questar can often outresolve an 8" Schmidt-Cassegrain on globular clusters, binary stars, and lunar and planetary details – with the Questar invariably exceeding Dawes’ limit for the best resolution available from an optical system of its aperture.

A second reason is the turbulent Earth atmosphere all telescopes must look through. In essence, when observing, you are usually looking through bubbles of disturbed air – microcells typically 4" in diameter in the layer of the atmosphere nearest the surface of the Earth. The image-blurring effect of these microcells is largely invisible as long as the column of light entering the telescope is smaller than the 4" diameter of the cells.

It was for just this reason that an aperture of 3.5" was originally chosen for the Questar. In average to mediocre seeing conditions, a 3.5" Questar will see through individual 4" microcells undisturbed, showing more detail than a larger scope that has to put up with the blurring of multiple turbulent cells.

Finally, there is the matter of contrast. The small secondary mirror of a Questar Maksutov scatters less light than a Schmidt-Cassegrain’s larger secondary. The secondary of an 8" Schmidt can be a full 3.45" in diameter, for example – a light-scattering obstruction almost as large as the entire 3.5" Questar aperture! In addition, a Questar’s central baffle tube is not merely black plastic or painted black to reduce reflections, as with lesser scopes, but actually contains 19 internal knife-edge baffles to eliminate low-angle reflections that no paint alone can stop. The result is that a Questar scatters less light from the bright areas of an image into the dark – crisply defining high contrast planetary and lunar details that a Schmidt can wash out in a haze of scattered light.

A large aperture scope does have greater light-gathering than a 3.5" Questar to capture additional faint deep space objects from a dark sky site. However, the higher contrast of a Questar lets the multitude of galaxies and nebulas within its grasp stand out more distinctly against a darker sky background, particularly from light-polluted suburban or city sites where a Schmidt’s greater light-gathering capacity submerges subtle low-contrast deep space details in a fog of city light.

As a Rolls-Royce is to automobiles, so is a Questar to telescopes – the very finest hand-crafted optical performance that money can buy.

But Questar’s quality does not stop with optical performance. What are costly options with other scopes – a full aperture glass solar filter, a premium Barlow lens, two premium eyepieces – are all standard on this 50th Anniversay Questar. Also standard are amenities that are simply unavailable on other scopes – a built-in glass solar filter for the finder that flips into place at the touch of a finger; an all-season star chart on the self-storing dewcap that slides forward to reveal a useful map of the Moon on the optical tube itself; and a velvet-lined lockable leather carrying case that has pockets for the scope’s included tabletop legs, its supplied second eyepiece, and its standard full aperture solar filter. The scope has a limited edition serial number to attest to its rarity. The performance of its optics are certified at 1/10th wave or better, with individual optical test result documents attested to and signed by the testing personnel. Both the optical tube and lens shade are silk-screened and etched, just like the original Questar. There are silk-screened and etched 50th Anniversary logos on the optical tube’s Moon map

The 3.5" Questar 50th Anniversary Edition is a complete telescope in a package weighing less than eight pounds. Remove it from its velvet-lined luggage-quality genuine leather case, attach its tabletop tripod legs that quickly set the scope up for polar operation hands-free tracking of near and deep space objects alike, place it on a table, and you have all the user-friendly controls of a great observatory scope at your fingertips.

Unscrew the dust cap, and you can begin to appreciate the attention to detail lavished on a Questar – for the dust cap is not flimsy press-fit plastic, but solid machined aluminum that threads into the barrel to afford absolute protection to the optics. The equatorial fork mount is machined of brushed aluminum, aircraft polyurethane painted for long life and good looks.

Look into the Questar’s premium 24mm Brandon eyepiece and you’re looking into a 4x finder with an exceptionally wide 12° field. A finger touch on a convenient lever at the rear of the scope changes the finder into a 53x telescope for observing the Moon, nebulas, and star clusters. Touch a second lever and a built-in Dakin Barlow instantly increases that eyepiece power to 80x for closer observing. Exchange the 24mm eyepiece for the supplied 16mm Brandon eyepiece and you extend the power range still further, to 80x and 120x, with a 6x finder. That’s a total of six magnifications from only two eyepieces. And optional higher and lower power eyepieces are available, for magnifications as low as 40x and as high as 320x. For observing comfort, a rare thing with many scopes, the optical tube tilts from side to side in its fork arms to the most convenient observing position (a feature unavailable on other scopes).

Observe through a 50th Anniversary Questar, and you’ll appreciate the attention to detail even more. The gearless 25:1 ratio slow motion controls operate with a smoothness and freedom from backlash unmatched by any other amateur telescope. The drive gear diameter is fully half the length of the telescope itself, for tracking precision that must be experienced to be believed. No tiny levers need be thrown to disengage the drive for manual operation, as a butter-smooth internal clutch made from micro-rolled discs of stainless steel lets you move the telescope at will. The large setting circles are not merely painted on, but are engraved and then paint-filled, to remain visible even after years of use. The right ascension setting circle is universal for use in both Northern and Southern hemispheres. ‘Jewel-like precision’ may be an overworked term, but it’s the only one that does justice to a 50th Anniversary Questar.

The Powerguide II DC drive system/drive corrector that is included with the 50th Anniversary Questar eliminates the need to stay near an AC power outlet to operate the scope’s motor. The Powerguide II’s DC servo quartz drive powers the scope’s drive motor for up to 50 hours from a single 9 volt transistor radio battery. This frees you forever from the need to stay near an AC outlet to observe the skies. The Powerguide II smoothly tracks the Moon, planets, star clusters, galaxies, and a host of other deep space objects across the heavens for you, keeping them centered in the eyepiece all night long. During the day, the Questar will also track the Sun, allowing you to observe sunspot patterns. You’ll do it in complete safety, as standard equipment glass full aperture and finderscope solar filters provide complete protection against the Sun’s fierce radiation for both your eye and your telescope.

Pushbuttons on the quartz-controlled Powerguide II hand control allow single axis guided astrophotography with 1.4x and 10x sidereal guiding rates in right ascension (dual axis with an optional declination motor). Other buttons control a built-in map light and the brightness of an optional illuminated reticle guiding eyepiece, and select either a lunar or sidereal drive rate. Another button selects northern or southern hemisphere operation, allowing you to use the Questar anywhere in the world without having to worry about finding the proper power frequency or voltage, or having the right kind of AC adapter. With the factory-installed Powerguide II, the 50th Anniversary Questar is truly a use-anywhere/use-anytime telescope!

The scope’s zero thermal expansion quartz mirror eliminates the minor need to refocus the scope as it cools to ambient temperature in situations involving large temperature swings. With a conventional Pyrex mirror telescope, if the difference in temperature between indoors and outdoors is 30 degrees or more Fahrenheit when the scope is taken outside, minor refocusing will be required as its mirror contracts while cooling down to the outdoor air temperature. Although the 3.5" mirror of a Questar cools down much more rapidly than a larger mirror, some people find the need for even an occasional refocusing to be annoying. Since a quartz mirror exhibits no expansion or contraction as temperatures change, the quartz mirror in this 50th Anniversary Questar eliminates any need for even minor refocusing. You can take the 50th Anniversary out into the coldest night or hottest day and use it instantly, without any need for it to acclimate to the ambient temperature.

The 50th Anniversary Questar uses high reflectivity silver mirror coatings with a protective overcoating of thorium fluoride instead of a standard Questar’s aluminum coatings with a silicon monoxide overcoat. The two silver mirrors provide a 10% light gain per surface, compared with aluminized mirrors. Magnesium fluoride antireflection coatings are used on the Grade A BK7 optical glass meniscus corrector lens on the scope, as they are optimally matched to the reflectivity response of the quartz/silver/thorium-coated mirrors.

Absolutely pinpoint 1/10th wave accuracy performance, total freedom from spurious color and distortion, with features that are simply unavailable in other scopes and an image clarity and contrast in a class all its own – a 50th Anniversary Edition Questar is truly a work of art, and like a work of art, unique. If you want the best small telescope in the world, and one of the rarest, this limited edition 50th Anniversary Questar is it. But the number of scopes still available is limited. If you want to be a member of the exclusive 50th Anniversary Edition Questar club, you’d better act soon.