50Th Anniversary 3.5", Broadband coatings, quartz mirror, Powerguide II drive/drive corrector

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The “Questar 50” is a blend of the original Questar Maksutov-Cassegrain telescope design, as first manufactured in 1950, with refinements in twenty-first century materials and technology that were undreamed-of 50 years ago. The Questar 50th Anniversary Edition is being manufactured and assembled in very limited quantities. Production of the Questar 50th Anniversary Edition will be limited to only 250 units worldwide.

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!

What is it about a Questar that makes it the best?

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

Hundreds of hours of painstaking, skilled effort and the finest materials available go into producing this optical and mechanical masterpiece. 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. The Powerguide II hand control stores neatly into a pocket in the door of the carrying case when not in use. 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.
Highest Useful Magnification:
This is the highest visual power a telescope can achieve before the image becomes too dim for useful observing (generally at about 50x to 60x per inch of telescope aperture). However, this power is very often unreachable due to turbulence in our atmosphere that makes the image too blurry and unstable to see any detail.

On nights of less-than-perfect seeing, medium to low power planetary, binary star, and globular cluster observing (at 25x to 30x per inch of aperture or less) is usually more enjoyable than fruitlessly attempting to push a telescope's magnification to its theoretical limits. Very high powers are generally best reserved for planetary observations and binary star splitting.

Small aperture telescopes can usually use more power per inch of aperture on any given night than larger telescopes, as they look through a smaller column of air and see less of the turbulence in our atmosphere. While some observers use up to 100x per inch of refractor aperture on Mars and Jupiter, the actual number of minutes they spend observing at such powers is small in relation to the number of hours they spend waiting for the atmosphere to stabilize enough for them to use such very high powers.
Visual Limiting Magnitude:
This is the magnitude (or brightness) of the faintest star that can be seen with a telescope. The larger the number, the fainter the star that can be seen. An approximate formula for determining the visual limiting magnitude of a telescope is 7.5 + 5 log aperture (in cm).

This is the formula that we use with all of the telescopes we carry, so that our published specs will be consistent from aperture to aperture, from manufacturer to manufacturer. Some telescope makers may use other unspecified methods to determine the limiting magnitude, so their published figures may differ from ours.

Keep in mind that this formula does not take into account light loss within the scope, seeing conditions, the observer’s age (visual performance decreases as we get older), the telescope’s age (the reflectivity of telescope mirrors decreases as they get older), etc. The limiting magnitudes specified by manufacturers for their telescopes assume very dark skies, trained observers, and excellent atmospheric transparency – and are therefore rarely obtainable under average observing conditions. The photographic limiting magnitude is always greater than the visual (typically by two magnitudes).

Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

1.3 arc seconds
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
The weight of this product.
7 lbs.
Heaviest Single Component:
The weight of the heaviest component in this package.
7 lbs.
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Based on Astronomy magazine’s telescope "report cards", scopes of this size and type generally perform as follows . . .
Terrestrial Observation:
Observing terrestrial objects (nature studies, birding, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial observing. Scopes with apertures under 5" to 6" are generally most useful for terrestrial observing due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes. 
Lunar Observation:
Visual observation of the Moon is possible with any telescope. Larger aperture scopes will provide more detail than smaller scopes, thereby getting a higher score in this category, but may require an eyepiece filter to cut down the greater glare from the Moon's sunlit surface so small details can be seen more easily. Lunar observing is more rewarding when the Moon is waxing or waning as the changing sun angle casts constantly varying shadows to reveal craters and surface features by the hundreds.  
Planetary Observation:
Binary and Star Cluster Observation:
Galaxy and Nebula Observation:
Terrestrial Photography:
Photographing terrestrial objects (wildlife, scenery, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial photography. Scopes with focal ratios of f/10 and faster and apertures under 5" to 6" are generally the most useful for terrestrial photography due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes.
Lunar Photography:
Photography of the Moon is possible with virtually any telescope, using a 35mm camera, DSLR, or CCD-based webcam (planetary imager). While an equatorial mount with a motor drive is not strictly essential, as the exposure times will be very short, such a mount would be helpful to improve image sharpness, particularly with webcam-type cameras that take a series of exposures over time and stack them together. Reflectors may require a Barlow lens to let the camera reach focus. 
Planetary Photography:
Star Cluster / Nebula / Galaxy Photography:
5 years
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Visual Accessories
Eyepieces (3)
8mm Brandon
by Questar
12mm Brandon
by Questar
32mm Brandon
by Questar
  • 1.25" 16mm and 24mm eyepieces (54x to 120x, depending on eyepiece and whether built-in 1.5x Barlow is used)
  • Built-in 4x finder (6x when 16mm eyepiece is used)
  • VHR silver coated and overcoated quartz mirror
  • Magnesium fluoride coated optics
  • Built-in star diagonal
  • Dual arm fork mount
  • Setting circles (r. a. circle power driven)
  • Powerguide II DC motor drive
  • Manual slow motion controls
  • Thread-in dust cap
  • 3.5" full aperture solar filter
  • Solar filter for finder
  • Tabletop tripod legs
  • Locking leather hard case
  • Self-storing dewcap with embossed star chart
  • Embossed Moon chart on scope barrel
  • Ten-year warranty (five years on coatings, two years on drive and focuser)
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Questar - 50Th Anniversary 3.5", Broadband coatings, quartz mirror, Powerguide II drive/drive corrector

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Questar - 50Th Anniversary 3.5", Broadband coatings, quartz mirror, Powerguide II drive/drive corrector
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Our Product #: Q50
Manufacturer Product #: 10514-50
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The Questar 50th Anniversary Edition blends the still-unsurpassed original Questar Maksutov-Cassegrain telescope design of 1950 with advances in twenty-first century materials and technology that were undreamed-of 50 years ago. The result is the best small telescope available anywhere. Production of this unique telescope will be limited to only 250 units worldwide . . .

. . . our 34th year