Questar 7″ Classic Titanium Maksutov-Cassegrain, Magnesium Fluoride AR and Silver Reflecting Coatings, Quartz Mirror

Description

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 uses the same optical materials and coatings combination as the renowned 50th Anniversary 3.5″ Questar, perhaps the ultimate small telescope. The Seven Classic’s zero thermal expansion quartz mirror eliminates the 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. This is particularly true with a relatively large aperture scope like this Seven Classic, which has an oversize 7.6″ primary 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 Questar Seven Classic Titanium eliminates any need for even minor refocusing. You can take it out into the coldest night or hottest day and use it instantly, without any need for it to acclimate to the ambient temperature.

This Questar Seven Classic Titanium 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 this scope, as mag fluoride coatings are optimally matched to the reflectivity response of the quartz/silver/thorium-coated mirrors.

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.

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 and a quartz mirror will prove to be an absolutely eye-opening astronomical revelation. It is a telescope you can live with comfortably for the rest of your life.

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