Youtor
Amazing Questar MaksutovCassegrain Telescope Field Edition Broadband Coating
YOUR LINK HERE:
http://youtube.com/watch?v=irLFFwE7fk0
The Questar Field Model telescopes are a Maksutov-Cassegrain based lens optimized for visual observing and for imaging with the popular film, CCD/CMOS camera sensors. With a suitable adapter one can actually take photographs through the eyepiece with gadgets as convenient as a smart phone. These are typically sold new for birders and nature studies, for law enforcement and wildlife conservation markets. The prices for the current versions of these telescopes, with provided accessories, start at $3,500.00. • There have substantial changes in how the optics are made, the design too has changed. While the eyepieces made for these early Questars, while satisfactory for terrestrial work are not compatible/interchangeable with any standard of eyepieces sold today; if one orders the newer style eyepiece holder then this opens the telescope to accommodating a greater variety and magnification range of eyepieces. • There can also be differences in the diameter of the Axial Port (rear center port, covered with a thread-on metal disc. The earlier Questars were made with a .950 incg Ø axial port. Those made today, and over recent decades too feature a 1.2 inch Ø axial port opening. • The two standard eyepieces provided with new Questar 3-½ astronomical telescope, or the one provided with the Field models in this era rely on an attachment mechanism where an aluminum cylindrical holder threads onto the top of the Control Box, then one can grasp the thin knurled rim of either the provided 40-80x or 180-160x eyepiece to thread it into the eyepiece holder. To adjust focus at the Finder setting of these older Questar telescopes one rotates the upper assembly of the eyepiece clockwise (in) or counterclockwise (out) to reach focus for the individual observer. This arrangement is shown below at left. • The modern eyepiece holder for the Questar is PN 13078 Diopter Adapter, shown below at right. This can replace the older style thread-in eyepiece holder of your telescope and this enables modern eyepieces 1- ¼ or threaded Brandon to be used with your telescope. This also incorporates a knurled black anodized upper assembly that can be rotated to allow you to focus any Questar Brandon eyepiece, and some third party eyepieces too, with the Questar telescope Finder. Note Company Seven does not recommend third party alternatives to the Questar Diopter Adapter. • The foam lining of the cases originally provided with these instruments from the 1960’s to the 1980’s was a lightweight, foam-lined brief case. By now the foam has spalled, and this can cause several problems for the telescope. • • The Serial Number letter codes do have the meaning. For example a SN incorporating “Z” indicates Zerodur mirror, “Q” indicates quartz optics, “BB” Broad Band Coatings, “DP” indicates a Duplex model. The lack of these letters would indicate the telescope is not equipped with that option. • • For Field, Ranger and Birder Models: F indicates a Field Model, X indicates a special version (Birder, etc.), and RF indicates Rapid Geared manual focus control. The serial number indicates the production sequence, so that SN 3000 for example was made some time after SN 2500. • • As far as the numbers go on production astronomical (consumer) 3-1/2 telescopes, a SN of “#265” indicates the 265th fork mounted Questar Standard model . This would have been made in June of 1957 with a Pyrex Primary Mirror and Magnesium Fluoride AR coatings. By 1958 Questar started the SN with a prefix code indicating the year of manufacture so “2-1020” describes a Standard model made in 1962 with Pyrex Primary Mirror and Magnesium Fluoride AR coatings. “8-DP-3701” indicates the 3,701 fork mounted Questar 3-1/2 made, as a Duplex in 1968. “3-5380” is a Standard sold in November 1973 with Pyrex Primary Mirror and Magnesium Fluoride AR coatings. “4-8755” indicates a Standard model made in June 1984 with Pyrex Primary Mirror and Magnesium Fluoride AR coatings. • • The year in which a telescope was assembled does not always correspond to when it was sold new. A telescope may have been assembled for stock late in one year then not sold until months later into the next year. • • Also note is possible that a telescope originally made as a Standard model might have been converted to a Duplex at some later date, and this would be in our records with the new Serial Number issued changed to read as a “DP”.
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