National Geographic NG90EQ owner manual Word about the TWO Eyepiece Ports

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 area slowly turn the slow-motion cable extending from the left side of the telescope until the object is centered again. If your setup was not accurate you will notice that the subject is moving very slowly either up or down. A slight turn of the declination slow-motion control knob extending from the back of the telescope will counteract this slight error (See Fig. 22).

(Fig. 22)

A WORD ABOUT THE TWO EYEPIECE PORTS

The NG90EQ is fitted with two eyepiece ports. The top port generally is used for astronomical viewing. The view you see will be right side up, but will be laterally reversed, like looking in a mirror. This is normal, and is of no consequence.

The rear port, with the 45º diagonal prism attached, is normally used for terrestrial, or land viewing. When an eyepiece is placed in the 45º diagonal prism the view is correctly oriented, like looking through a pair of binoculars, though with much higher magnifying ability.

The image produced by the telescope can be directed to one port or the other with the flip mirror on the main optical unit. In Fig. 18 the image is being directed to the upper eyepiece port. In Fig. 19 it is being directed to the rear optical port.

(Fig. 18) (Fig. 19)

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