Catadioptric (Lens/Mirror combos)

More Information  · Supplied Accessories  · Recommended Accessories  · Images of Some Features Price $199.50 List Price $318.95 Magnification 39x Field of view 1000 yards 68' Near Focus 15' Eye Relief 18mm Exit Pupil 2.41mm Twilight Factor 58.48 Weight 5 lbs. Aperture 3.5" Length 16" Armored Yes Waterproof Yes Warranty Limited Lifetime Photographic Focal Length 1250mm Photographic Focal Ratio f/14

• 90mm f/14 Maksutov-Cassegrain optics
• 8 x 21mm erect image finderscope
• 32mm Plössl eyepiece (39x)
• erect image 45° viewing angle
• T-threads on body allow easy attachment of DSLR or 35mm camera
• waterproof body
• nylon backpack carry case

    The Celestron C90 Mak puts good quality multicoated Maksutov-Cassegrain catadioptric optics into a waterproof body that will take unexpected downpours in stride. Like all Maksutov optics spotting scopes, such as the ultra-premium Questars, the C90 is exceptional for observing anything that is small and distant and needs a lot of power to resolve clearly. It provides sharp, high contrast images of distant birds and wildlife, details that are free from the distracting spurious color you’ll find in comparably-priced achromatic refractor spotters. Optically very nice, this Celestron 90mm Maksutov has the optical performance to keep you busy observing the land and sky for many years to come.

Features of this spotting scope . . .

• Maksutov-Cassegrain optics: 3.5" (90mm) aperture, 1250mm focal length, f/14 multicoated optical system. The 16" long optical tube weighs 5 lbs with finderscope and eyepiece attached.

• Multicoated optics: The system’s Maksutov corrector lens is fully coated on both sides with multiple layers of antireflection materials for high light transmission and good contrast.

• Internal focuser: Focuses by moving the primary mirror fore and aft in the optical tube by means of a large focusing knob on the rear cell.

• Close focusing: Twenty turns of the slow, but very precise, focusing knob of the C90 moves the focus from the horizon down to a very close 15’. This is not as great a burden as it might first seem, as only a few turns of the knob in the middle of its rotation range will cover most of the medium to long distance observing situations the C90 is designed for. However, the relatively slow multi-turn focusing makes the C90 more suitable for observing stationary targets from distant locations, rather than trying to follow fast-moving birds in flight.

• 45° viewing angle image-erecting diagonal: A 1.25" accessory holder attached to the rear cell of the scope holds the supplied 45° viewing angle erect image 1.25" diagonal (eyepiece holder) for visual observing. The correctly-oriented images in the 45° diagonal are identical to what you see with your unaided eye and in the supplied finderscope, to make it easier to follow moving subjects.

• Eyepiece: Fully multicoated 1.25" 32mm (39x) Plössl eyepiece with a 1.3° field of view (68’ at 1000 yards). While this Celestron C90 Mak has excellent optics with sharp images, its field of view is somewhat narrow, due to the scope’s long focal length. However, the narrow field is entirely in keeping with the primary task of the scope, that of long distance observing. The eyepiece has a usable eye relief of 18mm for eyeglass use. In addition, any of nearly 200 different 1.25" astronomical eyepieces can be used with the C90, giving exceptional flexibility in choosing observing magnifications. For example, the optional Celestron 8mm to 24mm zoom eyepiece listed below provides very flexible viewing, with a zoom range of 52x to 156x, allowing you to instantly modify the magnification to suit the target distance and lighting conditions.

• Finderscope: 8 x 21mm straight-through crosshair design with erect right-reading images that give you the same image orientation you see with your unaided eye. Three collimating screws let you line up the finder crosshairs precisely with the center of the eyepiece field. The finderscope must be removed from the scope before the scope is stored in its case, but a quick-release dovetail bracket makes removing the finder just a matter of seconds. The finder can be reinstalled on the scope just as quickly, and the dovetail bracket system assures that the finder will be properly lined up with the main optics once in place on the scope. The finderscope eye relief is quite short at 8mm. It will severely vignette the field of view for eyeglass wearers.

• Waterproof body: The waterproof body will take sudden showers in stride, although it is not guaranteed against total submersion in river or lake.

• Tripod adapter: The scope has a mounting shoe with two standard 1/4"-20 thread mounting holes to let you use it on any suitable heavy duty photo tripod. The front hole is for visual use. The rear hole will help better balance the scope on the tripod when a camera is attached for terrestrial photography.

• Built-in camera adapter: The 1.25" accessory holder at the rear of the scope has standard T-threads built in that allow you to connect a 35mm SLR or DSLR camera to the scope by simply adding an inexpensive optional T-ring to fit your camera. This converts the C90M to a very high power 1250mm focal length (25x) f/14 telephoto lens for long distance terrestrial nature photography. Such high magnification requires the use of a very sturdy photographic tripod for the sharpest images.

• Carry case: Nylon backpack style carrying case.

• Lifetime warranty: This Celestron spotting scope is protected by a limited lifetime warranty.