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NG90EQ
Maksutov-Cassegrain
Telescope
Instructions
and
Owner’s Manual
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Parts of your NG90EQ Telescope: A. Equatorial mount D E F A B C B. Counterweight shaft G C. Counterweight D. Slow-motion control knobs (2) E. 9-mm eyepiece L F. 25-mm eyepiece M G. 3X Barlow lens H. Main optical unit J K I. Accessory tray I H N J. Finder scope K. 45º prism L. Mounting plate M. Accessory tray screws (3) N. Tripod bolts (3) O. Tripod legs (3) O A. Equatorial mount G. 3X Barlow lens M. Accessory tray
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Introduction Congratulations on your purchase of a precision-crafted NATIONAL GEOGRAPHIC™ telescope. With proper care and handling of your telescope, you will enjoy the pleasure of looking at nature’s wondrous sights through the eye of this instrument for many years. The NG90EQ has been designed to provide views of the moon’s craters, Jupiter’s major moons, and Saturn’s rings, in addition to dozens of galaxies, star clusters, and nebulae. As a terrestrial (land) telescope, the NG
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ASSEMBLY 1) Carefully remove all parts from the cardboard cartons and lay them on a table or on the floor in order to take an inventory of all the pieces. Keep your box for storage or in case you ever need to ship your telescope. 2) Each aluminum tripod leg can extend to almost double its closed length. This enables the height of the telescope to be adjusted to comfortably suit most users. Each leg is equipped with a locking knob that can be loosened to perform this adjustment and
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(Fig. 2) (Fig. 3) 5) The main optical unit is attached to the equatorial mount with a black cast metal mounting plate. This mounting plate has four chromed screws mounted in it. Remove all four screws. The mounting plate has one smooth face and one face with small ridges. Place the smooth face against the underside of the main optical unit. Then insert the two slotted chromed s
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7) The counterweight balances your telescope and makes it easy to adjust and position. Hold the counterweight in your hand so you can see through the hole in the weight. Make sure that the black tightening knob on the counterweight is facing down. When you look through the counterweight, if you see that the hole is blocked by a metal rod, slowly turn the tightening knob counterclockwise to loosen it until you see that the hole is clear (see Fig. 8). Then insert the counterweight shaft t
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10) Remove the plastic dust cap from the upper eyepiece port and insert the 25-mm eyepiece into the eyepiece holder. Tighten the small set screw to hold the eyepiece securely in place. (See Fig. 15). (Fig. 15) 11) Remove the plastic dust cap from the rear eyepiece port and attach the 45º diagonal prism by turning its collar clockwise over the threaded piece on the back of the main optical unit (See Fig. 16 and Fig. 17).
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Complete the following settings in daylight: 1) Insert the 25-mm eyepiece into the eyepiece holder. Look at an easily recognizable, stationary object that is at least 500 feet away. Slightly loosen all locking knobs and move the telescope until the object is in the center of the field of view. Then bring the image into focus. 2) Firmly retighten the locking knobs so that the telescope is locked in position. 3) Look through the finder scope. If the object is not visible or centered
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You can also adjust the declination by raising or lowering the angle of the main optical unit until the arrow on the degree scale located on the side of the equatorial mount points toward the north latitude of your observing location. If you do not know your viewing position’s north latitude, you can call a local weather office or airport to find out. Use your finder scope to locate an object. Focus on the object and begin observing. As you notice the viewed object move across the viewing
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The two eyepiece ports can be used in another way. With an optional camera adapter and appropriate T-ring a 35-mm SLR camera body can be attached to the rear eyepiece port. The 45º diagonal prism must first be removed. With an eyepiece in the top eyepiece port and a camera body attached to the rear eyepiece port a subject can be observed with the eyepiece. Then by simply adjusting the flip mirror, a picture can be taken through the rear eyepiece port. FOCUSING FOR ALL VIEWING IS ACCOMPLI
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The level of magnification required depends on the object being observed. Optimal performance is obtained if the magnification is typically not more than appromiately 30X for every 10 mm of objective lens diameter. Magnification of around 265X or less is ideal for a telescope with a 90-mm diameter objective lens and is best for observing most celestial objects. A lower magnification power and a wider field of view are advisable for the observation of galaxies and nebulae. The highest magn
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When possible, avoid sudden temperature changes, as the moisture in the air will condense on the objective lens. Should this occur after bringing your telescope inside, leave the lens cap off the objective lens, tilt the objective (front) lens facedown, and wait until the telescope reaches room temperature. USING YOUR TELESCOPE FOR TERRESTRIAL VIEWING When viewing objects on land, the circular motions of the equatorial mount prove to be a distraction. We are much more familiar wit
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CARE AND CLEANING OF OPTICS Optical components of a telescope get dirty over time. Dirt or dust on a lens should be removed with the utmost care. A considerable amount of dirt or dust would have to accumulate on the optical surface before your view would be compromised. 1) Keeping dust caps on during storage and transport will reduce dust collection. 2) Condensation may collect on the optical surfaces when the telescope is not in use. Remove the dust caps and allow the moisture to
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The popular and more familiar constellations often provide the easiest landmarks to help find the planet’s locations and paths of orbit. Most people have looked up at the sky at night and seen some of the planets without even realizing it. A planet looks like a bright star but does not twinkle like a star does; it looks like a tiny ball. Venus, Mars, Jupiter, and Saturn are the easiest planets to view. Mercury is dimmer, usually below the horizon, and more challenging to find. Each of t
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2) Why can’t I see anything through my telescope? If you see only gray or black when looking through your telescope, even after searching for an object to view, it is very likely that you are using an eyepiece that is too powerful. To solve this problem always start with the lowest power eyepiece first, and only insert the higher-power eyepiece after you have located an object. 3) When I use my high-power eyepiece, everything looks much darker. Why? As magnification in a telescope in
