Questar Field Model, 90mm, 53/80x, case


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For observing distant subjects clearly, no other spotting scope beats the clarity and resolution of a Questar, a spotting scope that Cornell University's Living Bird magazine called "legendary" . . .
Our Product #: QF
Questar Product #: 10110

Product Description

One of our customers from Nebraska called up shortly after he received his Questar Field Model to say his scope clearly showed the power line into his neighbor's house. We didn't think that was all that impressive - until he told us his neighbor lived three miles away! As a review in Audubon magazine noted, "Brighter than reality, the Questar has unbelievably sharp resolution and an extremely flat field. It shows every feather from a half-mile away!" (The exclamation point is theirs.)

A Questar has no astigmatism or chromatic aberration - no optical problems of any kind - to detract from your enjoyment. The Audubon review added, "the Field Model is unrivalled as a catadioptric spotting scope. It sets the highest standards for both optical performance and convenience of use."

A review in Cornell University's Living Bird magazine said, "The legendary Questar. There's no question that for the right application this is a fantastic scope."

And just what is the right application? According to the Living Bird review, "there are times when the Questar is indispensable. During the World Series of Birding, the Lab team spied a white blob on an old water tower. Rick put his trusty Bushnell Spacemaster on it at 22x - still a white blob. Kevin tried the Kowa TSN-4 at 60x and saw a white blob that might be a large bird. Finally Todd trained the Questar on it, flipped to 80x, and got a crystal-clear image of a roosting barn owl."

What is the right application? It is any birding challenge where you need absolutely razor-sharp views of distant birds. The supplied standard equipment eyepiece gives you a basic 53x magnification. A built-in Barlow lens increases that power to 80x at the touch of your finger on a lever at the rear of the scope. Another lever instantly converts the 53x eyepiece to a 4x finder with an exceptionally wide 12 degree field of view (630' at 1000 yards). You never risk losing your subject as you move your eye from finder to eyepiece, because finder and eyepiece are one and the same. (Both provide erect but reversed mirror images.)

For those birders who prefer lower powers and a wider field for close-in birding, an optional 40x eyepiece is available that provides 60x when the built-in Barlow is used. With the optional 40x eyepiece in the eyepiece holder, the 4x finderscope magnification drops to 3x, but with an even wider field of view (14 degrees, which is a very wide 735' at 1000 yards). The 40x eyepiece can be substituted for the standard equipment 53x eyepiece at no extra cost, if the substitution is requested at the time your scope is ordered. The 40x eyepiece is also available for separate sale, to give you a total of four separate magnifications from only two eyepieces (using the scope's built-in Barlow lens to increase the power of each eyepiece). A rolldown rubber eyecup is provided on all eyepieces for eyeglass use, although eye relief is relatively limited at higher powers.

Because of its high power and its ability to focus as close as 8' (although with a very shallow depth of field at that close a distance), the Field Model is a marvelous long distance microscope for close-up studies of subjects that are too small or too dangerous or too fragile to examine at close hand - ant hills, bee hives, spider webs, etc. At its standard 53x magnification, subjects 10 feet away appear the same size as they would if you could get your eye within a mere 2.2" of them, with a field only 1.8" wide filling your eyepiece! Imagine your views of gape-mouthed chicks being fed in nearby nests, hummers at feeders, and more!

The black and satin-finished aluminum Field Model comes with a 3/16" thick machined thread-on metal protective dust cap. A slide-on metal lens shade improves both visual and photographic contrast. Other standard equipment includes a camera coupling set that lets you use the Field Model as a razor-sharp 1400mm (28x) f/16 telephoto lens by adding an optional Questar brand P-thread T-ring to fit your particular camera body.

The Field Model has extremely precise 50-turn knob focusing. (We Questar owners soon learn to roll the side of our finger along the side of the focusing knob to speed up focus changes, rather than turn, turn, turn with our fingertips.) Faster-acting 24-turn focusing is available as a factory-installed option for more quickly tracking moving birds and wildlife (although at the cost of increasing the close focus distance to 25' from the standard 8').

An optional roof prism image erector, #6351, is available to allow straight-through viewing (from inside a car being used as a mobile blind, for example, using an optional car window mount). There is a loss of field when the image erector is used (from 54' down to 47' with the 40x eyepiece), the lever that changes from finder to a high power view is disabled, and you can only change powers by changing eyepieces, as the Barlow and finder optics are no longer in the optical path.

Long-life aluminum mirror coatings and antireflection magnesium fluoride lens coatings are standard equipment for good light transmission and long life under adverse field conditions. However, a highly recommended option is the application of high transmission/low reflection broadband multicoatings to the Field Model's objective lens during manufacture. This multicoatings package (on the Questar model #QFB) also includes a change in mirror surface material from aluminum to higher reflectivity silver. The broadband coatings package gives you a full 22% gain in light transmission and contrast that's very useful for twilight viewing and photography. An optional thermally-stable Zerodur ceramic mirror is available in place of the standard Pyrex mirror (in the Questar model #QFBZ) for critical photographic situations that don't allow focus changes during wide temperature swings. This is helpful for use in difficult locations such as the Arctic or Sahara, but is usually not needed in the continental United States or Hawaii, as well as in most of Canada.

A foam-fitted waterproof hard case is standard equipment.

The Field Model has a ten-year Questar warranty (with a two-year warranty on the focuser mechanism).

As the review in Audubon concluded simply, "Questar is superb." If you want the world's very best spotting scope, a Questar is it. Period. Case closed.

Tech Details

Aperture 3.5"
Armored No
Exit Pupil 1.7mm @ 53x
Eye Relief 8mm
Field of view 1000 yards 45' @ 53x
Length 11"
Magnification 53/80x
Near Focus 8'
Photographic Focal Length 1400mm
Photographic Focal Ratio f/16
Twilight Factor 68.7 @ 53x
Warranty 10 years


Review by:
The Questar Field Model in an excellent/outstanding visual and photographic instrument . Used for bird watching at moderate to long distance it cannot be beat. Can be used close up as a low power microscope for nature and technical observation. (Posted on 10/6/2018)
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Supplied Accessories

  • Eyepiece
  • Built-in 1.5x Barlow and 4x finder
  • Lens shade
  • camera adapter
  • Dust covers
  • Hard case