Celestron NexStar 114SLT NEWTONIAN Manuel D'instructions page 16

COLLIMATION
The optical performance of your telescope is directly related to its collimation Collimation is the alignment of the optical
system Your Newtonian telescope was collimated at the factory after it was completely assembled However, the telescope
may have to be collimated after it's transported The only optical element that may need to be adjusted, or is possible, is
the tilt of the secondary mirror
To check the collimation of your telescope you will need a light source A bright star near the zenith is ideal since there is
a minimal amount of atmospheric distortion Make sure that tracking is on so that you won't have to manually track the star
Or, if you do not want to power up your telescope, you can use Polaris Its position relative to the celestial pole means that it
moves very little thus eliminating the need to manually track it
Before you begin the collimation process, be sure that your telescope is in thermal equilibrium with the surroundings Allow
45 minutes for the telescope to reach equilibrium if you move it between large temperature extremes
To verify collimation, view a star near the zenith Use your high power eyepiece — 9mm focal length It is important to center a
star in the center of the field to judge collimation Slowly move in and out of focus and judge the symmetry of the star If you
see a systematic skewing of the star to one side, then re-collimation is needed
To accomplish this, you need to tighten the secondary collimation screw(s) that move the star across the field toward
the direction of the skewed light These screws are located in the secondary mirror holder) Make only small 1/6 to 1/8
adjustments to the collimation screws and re-center the star by moving the scope before making any improvements or
before making further adjustments
To collimate your telescope, follow these steps:
1 While looking through a medium-to-high-power eyepiece, de-focus a bright star until a ring pattern with a dark
shadow appears Center the de-focused star and notice in which direction the central shadow is skewed
2 Place your finger along the edge of the front cell of the telescope (be careful not to touch the corrector plate), pointing
towards the collimation screws The shadow of your finger should be visible when looking into the eyepiece Rotate your
finger around the tube edge until its shadow is seen closest to the narrowest portion of the rings (i e , the same direction in
which the central shadow is skewed)
3 Locate the collimation screw closest to where your finger is positioned This will be the collimation screw you will need to
adjust first (If your finger is positioned exactly between two of the collimation screws, then you will need to adjust the screw
opposite where your finger is located)
4 Use the hand control buttons to move the de-focused star image to the edge of the field of view in the same direction that
the central obstruction of the star image is skewed
5 While looking through the eyepiece, use a Phillips head screw driver to turn the collimation screw you located in step 2 and
3 Usually a tenth of a turn is enough to notice a change in collimation If the star image moves out of the field of view in
the direction that the central shadow is skewed, than you are turning the collimation screw the wrong way Turn the screw in
the opposite direction, so that the star image is moving towards the center of the field of view
6 If, while turning, you notice that the screws get very loose, then simply tighten the other two screws by the same amount
Conversely, if the collimation screw gets too tight, then loosen the other two screws by the same amount
7 Once the star image is in the center of the field of view, check to see if the rings are concentric If the central obstruction is
still skewed in the same direction, then continue turning the screw(s) in the same direction If you find that the ring pattern
is skewed in a different direction, simply repeat steps 2 through 6 as described above for the new direction
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ENGLISH