9
FINDER SCOPE ALIGNMENT
Since a telescope has a narrow field of view by design, it can be challenging to locate a
particular star or planet. For this reason the telescope is fitted with a low-power, wide-
field miniature telescope called a finder scope. Always use your finder scope to locate
the object you want to view FIRST.
The finder scope should be aligned with the
main telescope tube
before you begin using the telescope,
in order that both
scopes are positioned to always provide exactly the same angle and view.
Note: Objects in the finder scope are upside down. This is normal and is common to all
astronomical telescopes.
Complete the following settings in daylight: WITH THE EQUATORIAL MOTOR
TURNED ‘OFF’ AND CLUTCH DISENGAGED.
1) Insert the 25-mm eyepiece into the eyepiece holder. Look at an easily recognizable,
stationary object that is at least 300 feet away. Slightly loosen all locking knobs and
move the telescope BY HAND 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 in the finder
scope, simply release one of the three small adjusting screws holding the finder scope
and reposition the finder scope until the object is centered within the X-shaped
crosshairs.
4) All screws should be completely tightened as soon as the view through the finder
scope coincides with the view of the main telescope.
5) This procedure may need to be repeated to ensure a perfect alignment.
THE EQUATORIAL MOUNT
The advanced, precision-engineered equatorial mount on the OR7500 moves the main
optical tube in a circular fashion. This is very important because it means that you can
set up your telescope to conveniently compensate for the rotation of the Earth, and
easily follow celestial objects and planets in their natural path or orbit in the night sky.
When you observe an astronomical subject through a telescope it will appear to move
across the viewing area. At medium-power magnifications the image can appear to
move across the whole viewing area in about 30 seconds. With a simple mounting
system, called an altazimuth mount, it can be difficult and frustrating to track an object
and keep it in view. The equatorial mount simplifies this operation, but it must be
correctly set up.
Pick up and rotate the whole telescope until the front of the main optical unit is facing
north. Look fairly high in the sky until you see the familiar star grouping called the Big
Dipper. By following an imaginary line up from the two end stars of the dipper (the
