Questar 7″ Classic Titanium Maksutov-Cassegrain, Broadband Coatings

Description

The Questar Classic Titanium weighs 19 pounds, 21 pounds if you add the thread-on dew shield). It measures 22.6″ long. The low profile mounting adapter block on the underside of the Classic Titanium has both 1/4″-20 and 3/8″-16 mounting holes to allow to be installed on the Questar Equatorial Fork Mount (our part #20004) and Questar Large Classic Titanium Pier (our part #29338) for astronomical use. It is well-balanced and relatively light, allowing it to be mounted on any suitably sturdy tripod for terrestrial operation. It can also be adapted to your own equatorial mount with minimal effort.

This Questar Seven Classic Titanium has a broadband dielectric multicoatings package that includes ultra-high transmission/low reflectivity broadband dielectric multicoatings on both sides of its objective lens for a light loss of less than 1/10th of 1% per surface for the brightest possible images. This compares with a light loss of 1% per surface with standard magnesium fluoride antireflection coatings. This multicoatings package also includes high reflectivity silver mirror coatings with a protective overcoating of thorium fluoride instead of standard aluminum coatings with a silicon monoxide overcoat. The broadband coatings package gives you a full 22% overall gain in light transmission and contrast that’s very useful for photography and when viewing faint deep space objects.

This broadband coatings package is not recommended if you live full time on ocean-front property, or spend much of the year at the seaside. Constant exposure to salt air can adversely affect the silver mirror coatings. Occasional visits to the shore are not a problem, only extended stays (particularly if the scope is not packed away in its case when not in use). Adding a few packets of desiccant (silica gel or similar, available at most camera stores) to the case to absorb moisture when near large bodies of salt water would be a helpful preventative measure in any event.

A thermally stable Zerodur ceramic mirror is also available as an option in place of the standard Pyrex mirror. As with any Pyrex mirror telescope, if the difference in temperature between indoors and outdoors is 30 degrees or more when a Questar is taken outside, minor refocusing will be required as its mirror contracts while cooling down to the outdoor air temperature. Some people find the need for even an occasional refocusing to be annoying. Since a Zerodur mirror exhibits virtually no expansion or contraction as temperatures change, this option eliminates this need for refocusing. This option is well worth considering due to the large thermal mass of the 7″ mirror and its consequently longer cool-down time than a smaller scope. I have both broadband coatings and a Zerodur mirror on my Questar Seven and can recommend them without reservation.

The Questar Seven Classic Titanium comes in a high impact ABS plastic sealed carrying case with wheels and transport handle. A basic 35mm camera coupling set is also included (needs a Questar T-ring to connect to your camera).

This Questar is protected by a ten-year Questar warranty (two-year warranty on the focuser mechanism and five years on the broadband coatings).

Absolutely pinpoint resolution, total freedom from spurious color and distortion, with an image clarity and contrast in a class all its own – a Questar is truly the Rolls-Royce of telescopes. For those individuals who appreciate the very finest that life has to offer, a Questar Seven Classic Titanium with broadband optical coatings will prove to be an absolutely eye-opening astronomical revelation.

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