Konus Maksutov-Cassegrains

More Information  · Supplied Accessories  · Images of Some Features Price $219.00 Shipping $30.00 List Price $347.00 Highest Useful Magnification 200x Visual Limiting Magnitude 12.3 Focal Length 1200mm Focal Ratio f/13.3 Resolution 1.29 arc seconds Aperture 3.5" Warranty 1 year

The scope’s equatorial mount has an adjustable height tripod. A convenient battery-operated motor drive makes it easy to keep the Moon and planets in the field of view for extended no-hands viewing sessions. The mount also has manual slow motion controls, should your motor’s battery die in the middle of an observing session.

The 90mm Konus Maksutov is not a scope for everyone. However, if you want to view the solar system in detail for not a lot of money, this may be just the scope for you.

This Telescope’s Optical System . . .

• Compound optical design: 1200mm focal length 90mm aperture f/13.3 all-glass Maksutov-Cassegrain lens/mirror optical design.

• Multicoated optics: The Maksutov corrector lens at the front of the scope has antireflection multicoatings on both sides of the lens for high light transmission and good contrast.

• Focuser: A knob at the rear of the optical tube moves the primary mirror back and forth internally to focus the telescope. The focuser is very precise, requiring twenty turns to go from its closest terrestrial focus to infinity, but only a few turns are required to move from solar system objects (such as the Moon) to objects at infinity (such as a star cluster).

• Star diagonal: A built-in flip mirror star diagonal directs the incoming light either to an eyepiece holder at the top of the scope or to the Cassegrain focus at the rear of the scope. The eyepiece holder at the top of the scope provides a 90° viewing angle for comfortable viewing when looking at the sky. It shows the mirror image astronomical view normal for a compound telescope (objects are reversed left for right).
  When the internal mirror is flipped and the light is directed to the Cassegrain focus at the rear of the scope, there are two observing possibilities. The first is to thread on the supplied 45° viewing image-erecting diagonal that shows erect right-reading images (printing reads correctly from left to right). This is useful for observing things on the ground or for identifying lunar craters when using a Moon chart that shows the Moon as it appears to the unaided eye.
  The second possibility is to replace the image-erecting 45° diagonal with an optional straight-through camera adapter for lunar and terrestrial photography.

• Two eyepieces: You get two good quality medium power 1.25" eyepieces – a 10mm (120x) and a 17mm (70x). 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 Motormax 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 neutral grey color cuts the glare of the brightly lighted Moon and improves the contrast. This makes it is easier for you to see faint details that might otherwise be washed out by the brightness of the lunar surface.

• Finderscope: An 8 x 21mm straight-through finder attaches to the side of the optical tube. If properly collimated (aligned) with the view through the main telescope, the crosshairs of this erect image/right reading finder 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 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.

• 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 follow manually 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 2.4’ tall to 4’ to accommodate a variety of observer heights. The tripod includes an accessory shelf that holds your eyepieces and accessories.