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How to Adjust a Celestron FirstScope

The Celestron FirstScope is a basic, beginner's tabletop telescope. It requires only the simplest assembly, and it is compact and easy to store. To use it, you just set it on a flat surface, point it to the sky and look through the eyepiece as you move the tube in the direction of the object you want to observe. Very little adjustment is necessary for getting the most out of this simple telescope. You can, however, adjust the secondary mirror in the event that your FirstScope shows signs of optical distortion.

Things You'll Need

Small Phillips-head screwdriver

Instructions

- 1
  Loosen the thumbscrews below the eyepiece on the focusing mechanism that is located on top of the FirstScope telescope tube.
- 2
  Grasp the eyepiece by its plastic ring and pull it out of the focuser.
- 3
  Turn the focusing ring inward as far as it will go by turning the focusing knobs at the side of the focusing assembly away from you (clockwise). Make sure that the silver-colored focusing tube extension, which has ridges in the back, is not visible at all.
- 4
  Look through the focusing tube so that you see your own eye in the mirror at the base of the tube.
- 5
  Alternately tighten and loosen the three secondary mirror screws on the side of the telescope tube closest to the focuser until your eye appears clear in the mirror. The two top screws are diagonal to the focuser, about a half-inch in from the end of the tube. The third screw is about a half-inch inward from the bottom end of the telescope tube.
- 6
  Replace the eyepiece and tighten the thumbscrews so that it is securely placed in the focuser. Focus on a pattern in the sky and look at it carefully to make sure the pattern appears symmetrically in the viewfinder. If it appears skewed to either side, repeat the previous steps.

Astronomy