Collumnating a Telescope

If you are not seeing an image in your reflector telescope or the image is dim or not clear you probably need to columnate you scope.  A reflector telescope uses two or more mirrors to bring the image to the eyepiece focal point.  If the mirrors are not aligned you wil not see an image. 

As you can see in the picture the lighe enters the telescope and hits the primary mirror which has a curved surface.  The curved surface returns the light to a point.  That point should be in the center of the secondary mirror. The secondary mirror then reflects the light to the eyepiece.

Collumnating the telescope is the process of aligning the mirrors so that the focal point is at the center of the wywpiece.  This is accomplished by truning small screws on the back of each mirror.  There are several tools that help wiht this process.  I will explaing each of these tools.

Laser Collumnator

A laser colmnator is the size of an eyepiece so it can fit in your telescopes focuser.  IT is a useful tool for collumnating your telescope.

After placing the laser collumnator in the focuser you adjust the secondary mirror until the beam hits the center of teh primary mirror.  Many telescopes have a small circle at the center of the primary mirror.

Next you adjust the screws on the primary mirror until the beam hits the center of the secondary mirror.

Finally you adjust the secondary so that the beam hits the center of the eypiece.  This may cause the beam to move from the center of teh primary if you are not careful.  The trick is getting all three points aligned which may require several rounds of adjustments.

Eyepiece Collumnator

There is another less expensive device that can be just as efective.  An Eyepiece collumnator has a mirror and crosshairs that are used to collumnate a telescope.