Celestron PowerSeeker 80EQ Telescope PowerSeeker 60, 70, 80, 114, 127 EQ Manua - Page 27
Aligning the Primary Mirror, Night Time Star Collimating, Procedure Please read
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Aligning the Primary Mirror Now adjust the primary mirror screws to re-center the reflection of the small secondary mirror, so it's silhouetted against the view of the primary. As you look into the focuser, silhouettes of the mirrors should look concentric. Repeat steps one and two until you have achieved this. Remove the collimating cap and look into the focuser, where you should see the reflection of your eye in the secondary mirror. Newtonian collimation views as seen through the focuser using the collimation cap Secondary mirror needs adjustment. Primary mirror needs adjustment. Secondary Mirror Primary Mirror Mirror Clip Both mirrors aligned with the collimating cap in the focuser. Both mirrors aligned with your eye looking into the focuser. Figure 7-1 PowerSeeker 114EQ Night Time Star Collimating After successfully completing daytime collimation, night time star collimation can be done by closely adjusting the primary mirror while the telescope tube is on its mount and pointing at a bright star. The telescope should be set up at night and a star's image should be studied at medium to high power (30-60 power per inch of aperture). If a nonsymmetrical focus pattern is present, then it may be possible to correct this by re-collimating only the primary mirror. Procedure (Please read this section completely before beginning): To star collimate in the Northern Hemisphere, point at a stationary star like the North Star (Polaris). It can be found in the north sky, at a distance above the horizon equal to your latitude. It's also the end star in the handle of the Little Dipper. Polaris is not the brightest star in the sky and may even appear dim, depending upon your sky conditions. For the Southern Hemisphere, point at Sigma Octantis. Prior to re-collimating the primary mirror, locate the collimation screws on the rear of the telescope tube. The rear cell (shown in Figure 7-1) has three large thumbscrews (on some models they are not thumbscrews) which are used for collimation and three small thumbscrews which are used to lock the mirror in place. The collimation screws tilt the primary mirror. You will start by loosening the small locking screws a few turns each. Normally, motions on the order of an 1/8 turn will make a difference, with approximately a 1/2 to 3/4 turn being the maximum required for the large collimation screws. Turn one collimation screw at a time and with a collimation tool or eyepiece see how the collimation is affected (see the following paragraph below). It will take some experimenting but you will eventually get the centering you desire. It is best to use the optional collimation tool or collimating eyepiece. Look into the focuser and notice if the secondary reflection has moved closer to the center of the primary mirror. 27