The Importance of Collimation – Part 2

The Importance of collimation Parts 2 and 3 explain how to use a laser collimator. As each telescope is different, you will need to refer to your manual on how you adjust your primary and secondary mirror using a screwdriver or allen keys.

First off you put the laser collimator into the focuser just like a normal eye piece. Turn the laser on. This will project  the laser beam into the scope, placing a dot onto the primary mirror and then reflecting the beam onto the secondary mirror and then back into the collimator. Sounds complicated doesn’t it.

In collimating the telescope, always collimate the secondary mirror first before the primary mirror. If you don’t do the secondary mirror  first, the primary mirror will be thrown out of alignment when you eventually align the secondary mirror.

Secondary Mirror Out of Alignment ( Click for Larger Picture )

Secondary Mirror Out of Alignment ( Click for Larger Picture )

Look down the front of the tube at the primary mirror. Depending on your scope you may see a donut shaped mark in the center of the primary mirror.

The picture on the left shows the donut or hollow circle of my Celestron 130SLT scope… marking the center of the Primary Mirror.

You can see the red dot of the laser is at the eleven o’clock position in reference to the donut. The red dot is not inside the boundaries of the donut so this means that my secondary mirror is not aligned and images seen in my telescope will not be great.  The further the red dot is away from the donut, or center of the primary mirror, the worse the image.

Secondary Mirror Aligned ( Click for Larger Picture)

Secondary Mirror Aligned ( Click for Larger Picture)

With my telescope, I adjust the secondary mirror using allen keys . Refer to your manual for your telescope on how to do this. Each adjustment will move the red dot vertically or horizontally.

Keep on making the adjustments until you have the red dot of the laser beam perfectly within the boundaries of the donut shape.

Once it is inside the donut, you know the laser beam is aligned perfectly with the centre of your primary mirror.

Now you can look at lining up your primary mirror…… descibed in the next post.

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~ by sydneystargazers on October 10, 2009.

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