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Questar logo from 1990's (27,482 bytes)


"it is simply amazing to resolve details as fine as a bicycle spoke one mile distant on a calm day!"

Questar Field Model Telescope (61,565 bytes). The Questar Field Model is considered by many to be the ultimate medium to long distance portable spotting scope in terms of reliability, convenience, and sheer optical performance. For situations requiring long focal lengths, no other telescope similarly compact telescope matches the Field Model's resolution and image contrast. Aside from the quality of optics, the Questar telescopes include patented devices to insure these instruments are compact, free of periodic adjustments, and user-friendly. Some years ago "Audubon" magazine published a comparative review of spotting telescopes and concluded the Field Model was the standard of excellence against which all others were measured.

Right: Field Model telescope with Lens Shade retracted (61,565 bytes).
Click on image to see enlarged view (93,310 bytes).

The Field Model incorporates a Control Box providing the observer with the choice of three magnifications per eyepiece (Finder, Low and High Power) so without having to look away from the eyepiece the observer can vary magnifications over a broad span. The Control Box employs two control levers, one of these employs the built in Barlow high magnifications lens. The other control dials in a Prism (also within the Control Box) to divert the incoming light beam from the telescope main optical tube 90 degrees up to the eyepiece. With this Prism in line the Axial Port is blocked. With the Prism moved out of the way by rotating the Control dial clockwise by 45 degrees then the Axial Port has clear access to the telescope for another eyepiece, a Questar Image Erecting Prism, or Camera Adapter. With the internal Prism moved aside the eyepiece port also has clear access to the Finder. So, one can be imaging through the Axial Port while simultaneously looking at the target through the Finder waiting for the object to be positioned just right prior to snapping the photo.

To place the eyepiece at a most comfortable position for the observer, particularly when looking over a berm or other concealed position, the entire optical tube assembly can be rotated within the tripod mounting collar clockwise to the right or counterclockwise to the left. To rotate the barrel simply grasp the fork mount with one hand to steady the set, then with the other hand grasp the Control Box to rotate the optical tube.

The telescope is provided with a 32 mm Questar Brandon eyepiece providing 3X in Finder Mode, 40X showing a field of view 1.2 degrees wide, and approximately 75X in the High Power setting. Company Seven can provide an alternative Questar Brandon or third party eyepiece, applying a credit from the Brandon.

As a nominal 1,280 mm telephoto lens, the 10-3/4 inch (27.3 cm) long Field Model optical tube assembly is comparable in physical size to a 250mm f/2.8 lens, and yet it weighs less than 3 pounds - 51.0 oz. / 1,445 g to be exact. A variety of other photographic and visual accessories remain available to suit our customers growing ambitions. All of these can be stored in the provided watertight carrying case.

The Questar 3-1/2 astronomical and terrestrial telescope barrels incorporate a slip on Dew Shield covered in a rolled aluminum sheet that is finished to match the optical tube of the telescope. The Dew Shield is lined with a felt like material so that it moves smoothly, and without scraping the barrel.

The only accessory one needs to put this telescope into service is a suitable Field Tripod.

Questar Field Model with Image Erecting Prism (42,858 bytes).
  • When observing with an eyepiece at the Visual Port (shown above right), then the image in the eyepiece will appear correct right side up, but is reversed left to right. Few people using this for nature watching complain about this since the view is notably better at higher magnifications which may be used occasionally for birding and more often in astronomy.

  • The telescope can be furnished with an optional 45 degree angled image erecting prism diagonal (shown at right) which then provide images which are correct right side up, and left to right. This tends to be selected by few of our customers, including nature watchers since the view is less crisp and clear (than the mirror diagonal) at higher magnifications which may be used occasionally for birding and more often in astronomy.

Right: Questar Field Model with optional Questar Image Erecting Prism and second Eyepiece (42,858 bytes).
Click on image to see enlarged view (93,310 bytes).

Lacking the Fork Mount that is provided with the Standard model for example frees the observer or photographer to travel with a much more compact, lighter weight arrangement. Those of our customers who would prefer to have both the astronomical capability of the Fork Mounted Questar with the high performance of this Field Model should consider the versatile Questar Duplex telescope.

Whenever in doubt about how to choose or configure your Questar, feel free to contact Company Seven to discuss your thoughts.


Questar Field Model Control Box (61,565 bytes). Optical & Mechanical Characteristics:

  • Design: Maksutov-Cassegrain Catadioptric
  • Standard Corrector Lens: BK7, MgF2 AR Coated; multilayer dielectric coatings optional
  • Primary Mirror: Pyrex substrate, aluminum coated with SiO overcoat; Zerodur substrate optional
  • Primary Mirror Diameter: 96mm (3.78 inches)
  • Standard Secondary Mirror: aluminum coated with SiO overcoat; silver with ThF4 overcoat optional
  • Secondary Mirror Diameter: 29mm (1.14 inches)
  • Effective Aperture: 89mm (3.5 inches)
  • Finder Focal Length: 100mm (3x with standard 32mm ocular)
  • Integral Barlow: typically between 1.5X to 2X (Company Seven will provide the data after testing)
  • Barrel Material: machined aluminum
  • Barrel Finish: satin Medium Blue or Black Anodized finish
  • Focus Mechanism: manual, with high speed gearing
  • Finish: aluminum components anodized natural, dark blue, or black
  • Weight: telescope weight is less than 3 lbs, or 12 lbs for the complete set in it provided case
  • Carrying Case: waterproof hard plastic construction, 18-1/2 x 14-1/2 x 8 inches / 47 x 37 x 20 cm
  • Focus Range: 6 Meters/ 20 feet to infinity*
  • Optical Resolution 1.3 Arc Second
  • f-ratio: 14.4 at 1,280mm
  • Spectral response: 350 to 1500nm, optional systems with wider spectral response available.

* Focus distances may vary somewhat with eyepiece choice, and users need to correct for less than perfect vision.

Right: Rear view of Field Model telescope showing the Control Box. Note how the barrel can be rotated within the cradle to position the eyepiece at the convenience of the observer (61,565 bytes).
Click on image to see enlarged view (93,310 bytes).

For a good overview of the decision making process of buying a Questar we suggest you read our article Selecting an Astronomical Questar Telescope. While this is geared more towards the astronomical 3-1/2 inch models furnished with a Fork Mount, there are good explanations of the various configurations and explanations of the major optical and accessory choices which apply to most other consumer models (Field, Birding, and the larger 7 inch models).

For current dimensions and a construction overview of the Questar Field Model telescope sold by Company Seven download the Questar illustrated two page brochure from Company Seven's Library. Download size is 1,563,246 bytes (in Acrobat Reader ".pdf" format).


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