Collimation Of A Newtonian Telescope - Celestron ASTROMASTER 70EQ Mode D'emploi

COLLIMATION OF A NEWTONIAN TELESCOPE

While your telescope requires little maintenance, there are a few things to remember that will ensure your telescope
performs at its Collimation is the process of aligning the mirrors of your telescope so that they work in concert with each
other to deliver properly focused light to your eyepiece By observing out-of-focus star images, you can test whether your
telescope's optics are aligned Place a star in the center of the field of view and move the focuser so that the image is
slightly out of focus If the seeing conditions are good, you will see a central circle of light (the Airy disc) surrounded by a
number of diffraction rings If the rings are symmetrical about the Airy disc, the telescope's optics are correctly collimated
Correctly Aligned
Collimation is a painless process and works like this:
Pull off the lens cap which covers the front of the telescope and look down the optical tube At the bottom you will see the pri-
mary mirror held in place by three clips 120º apart, and at the top the small oval secondary mirror held in a support and tilted 45º
toward the focuser outside the tube wall
The secondary mirror is aligned by adjusting the three smaller screws surrounding the central bolt The primary mirror is adjusted
by the three adjusting screws at the back of your scope The three locking screws beside them serve to hold the mirror in place
after collimation
22 I ENGLISH
Primary Mirror
Needs Collimation
Focuser
Support for
secondary mirror
Secondary Mirror