National Geographic NG90EQ manual

NG90EQ Maksutov-Cassegrain Telescope Instructions and Owner’s Manual[...]

2 A. Equatorial mount G. 3X Barlow lens M. Accessory tray screws a. Counterweight H. Main optical unit N. Tripod leg bolts B. Counterweight shaft I. Accessory tray O. Tripod Legs C. Slow-motion control knobs J. Finder scope D. 9mm eyepiece K. 45º Diagonal prism E. 25mm eyepiece L. Mounting plate WARNING! NEVER aim your telescope at the sun or even[...]

3 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 thr ough the eye of this instrument for many years. The NG90EQ has been designed to provide views of the moon’s craters, Jupi[...]

4 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[...]

5 (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 f our 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[...]

6 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 tight ening knob on the counterweight is facing down. When you look through the counterweigh t, if you see that the hole is blocked by a metal rod, slowl[...]

7 10) Remove the plastic dust cap from t he 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 t he rear eyepiece port and attach the 45º diagonal prism by turning its collar clock wise over th[...]

8 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 [...]

9 You can also adjust the declination by raising or lowering the angle of the main optical unit until the arrow on the degree scale loca ted 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 f[...]

10 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 re moved. With an eyepiece in the top eyepiece port and a camera body attached to the rear eyepiece port a subject can be observed with [...]

11 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 c[...]

12 When possible, avoid sudden temperature c hanges, as the moisture in the air will condense on the objective lens. Should this o ccur 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[...]

13 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 considerabl e 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 colle[...]

14 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 twin kle like a star does; it looks like a tiny ball. Venu[...]

15 2) Why can’t I see any thing 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 eyepie[...]