Omegon AZ mount, Instruction Manual

Page: 41 / 139

3.2 Adjusting a Newtonian telescope
A Newtonian telescope needs to be adjusted now and again. Only when well collimated will the optics provide
you with optimal performance and can you benefit from a sharp and a high contrast view. The telescope mirrors
will have been pre-set at the factory, but transport can throw this off slightly.
Before you begin with the adjustment, it is a good idea to check whether the mirrors actually are out of
alignment.
In order to discover this, find the polar star with your telescope, centre it in the field of view and defocus it.
Indications that the mirrors are in collimation:
The star has now become a round shape with a black circle in the centre. You could compare this shape to that
of a donut. Now pay particular attention to the central area shading, this should be precisely in the centre of the
disc. In good seeing conditions you will also be able to see several concentric symmetrical diffraction rings.
Indications that the mirrors are out of collimation:
The star has now become a round shape with an interior black circle. However, the central shading is no
longer exactly central but has shifted to one side. The diffraction rings around the shading are also not arranged
symmetrically.
40
correctly adjusted
has to be collimated