More Information  · Supplied Accessories Price $219.00 Shipping $25.00 List Price $559.95 Highest Useful Magnification 167x Visual Limiting Magnitude 12.3 Focal Length 1000mm Focal Ratio f/11.1 Resolution 1.29 arc seconds Aperture 3.5" Net Weight 21 lbs. Ship Weight 27 Warranty 1 year

The optical quality of this Konus is surprisingly good. Its achromatic refractor optics and sensible choice of magnifications provide you with detailed and high contrast views of the Moon, planets, binary stars, and star clusters – as well as the brighter nebulas and galaxies.

The construction of the mount is also first rate, with an adjustable height tripod, slow motion controls, and setting circles to help you locate object too faint to see through the finderscope. It even includes a battery-powered motor drive to automatically follow the stars and planets across the skies as you observe at your leisure. An unexpected bonus is the two soft carry bags with shoulder straps, one for your mount and tripod and the other for your optical tube. They make transporting your scope easy. Also included are large scale Moon and sky maps and a CD-ROM with a superb planetarium/star charting software program to help you find your way around the sky.

The 90mm Konus has a light grasp 165 times that of the sharpest eye, and almost thirteen times the eye’s resolving power (the ability to see small details). Combine that light grasp and resolving power with the highly usable 59x and 100x magnifications of its two quality Plössl eyepieces and you have the ability to see many, many celestial details that are simply invisible to the unaided eye – all at a price no higher than that of lesser quality department and toy store telescopes.

This Telescope’s Optical System . . .

• Refractor optical tube: 90mm (3.5”) aperture air-spaced two-element crown and flint glass achromatic lens. 1000mm focal length f/11.1 all-glass optics. No plastic lenses.

• Multicoated optics: The two-element objective lens has antireflection multicoatings for high light transmission and good contrast.

• Dew shield: A dew shield (an extension of the optical tube that’s threaded onto the front of the objective lens) slows the formation of dew on the lens in cold weather. This extends your undisturbed observing time.

• Rack and pinion focuser: The well-made 1.25” focuser has dual focusing knobs for precise image control with either hand. The large focus knobs are easy to operate, even while wearing gloves or mittens in cold weather.

• Star diagonal: The 90° viewing angle 1.25” star diagonal (eyepiece holder) allows comfortable viewing when looking overhead at the sky. It provides the normal mirror image astronomical view (objects are reversed left for right).

• Two eyepieces: You get two good quality medium power 1.25” eyepieces – a 10mm (100x) and a 17mm (59x). Both eyepieces are a higher quality four-element Plössl optical design than you’ll find in most other telescopes in this price range. They have antireflection multicoatings on their lens surfaces for sharp images and very good contrast. Instead of providing low quality eyepieces that give unrealistically high (and often unusable) magnifications, Konus provides higher quality eyepieces with powers you can use and enjoy every night you take your Konusmotor 90 out to observe. Optional eyepieces are available to let you extend your magnification range significantly.

• Moon filter: You get a 1.25” optical glass Moon filter that threads into the base of the eyepieces. Its green color cuts the glare of the brightly-lighted Moon and improves the contrast so it is easier for you to see faint details that might otherwise be washed out by the brightness of the lunar surface.

• Finderscope: A 6 x 30mm straight-through viewing crosshair finder attaches to the side of the optical tube. If properly collimated (aligned) with the view through the main telescope, its crosshairs will help you center distant objects in the telescope so you don’t have to search for them using the narrow eyepiece field of view.

This Telescope’s Mount . . .

• Equatorial mount: The sturdy equatorial mount is designed for astronomical observing. By aligning the mount on the north celestial pole, the supplied motor drive can automatically follow the motion of the planets and stars as they travel east to west across the sky. A counterweight on the opposite side of the mount from the telescope balances the weight of the optical tube and makes it easy to move the scope effortlessly from one part of the sky to another.

• Motor drive: The supplied user-installed single axis battery-operated right ascension motor drive has a variable speed control to match the slightly different speeds at which the Moon, planets, Sun, and stars move across the sky. This keeps objects from drifting out of the field during long observing sessions, or while several people in a row observe the same object. The drive runs up to 40 hours from one 9-volt transistor radio battery (depending on ambient temperature, as low temperatures reduce battery capacity).

• Setting circles: Setting circles (graduated scales marked in either hours and minutes or degrees) are provided in both right ascension (the east/west position of objects in the sky measured in hours and minutes) and declination (the north/south position measured in degrees). These allow you to align the scope on the approximate position of an object in the sky by using its r. a. and dec coordinates from a star chart – before you search for it in the finderscope and eyepiece. Setting circles can reduce the time it takes for you to find the fainter and more difficult deep space objects.

• Manual slow motion controls: There are two slow motion control knobs connected to the mount by long flexible cables so they are easy to reach while observing. One controls the scope’s motion in declination (the north/south direction in the sky). Turning this knob enables you to correct for any north/south drift a celestial object may take as it drifts across the sky, due to an improper alignment of the scope on the north celestial pole when you first set it up. The second controls the scope’s motion in right ascension (the east/west direction in the sky). Turning this knob enables you to manually follow the motion of celestial objects as they travel from east to west across the sky, should the battery in your motor drive die when you’re out observing.

• Tripod: The aluminum tripod easily adjusts from 2.2’ tall to 3.5’ to accommodate a variety of observer heights. As with all refractor telescopes that have an eyepiece at the bottom of a long tube, however, most observers will that find a seated observing position is more comfortable for extended viewing sessions, particularly when observing objects near the zenith (directly overhead). The tripod includes an accessory shelf that holds your eyepieces and accessories.

• Moon and sky maps: The large fold-out full color maps will help you learn the skies and the face of our nearest celestial neighbor. The Moon map has 276 craters and features labeled to help you find your way around the lunar surface. The sky map is a detailed chart of the entire sky, both northern and southern hemispheres, so you can learn the constellations and major stars and deep sky features easily.

• Software: The supplied Windows-based CD-ROM of planetarium/star charting software is one of the most sophisticated and flexible available. You can use it to print out detailed star charts to help you locate stars, planets, galaxies, asteroids, comets, star clusters, and more. You can also use it to print out charts showing the positions of the moons of Mars, Jupiter, Saturn, Uranus, and Neptune so you can i