Orion NEWTONIAN ASTROGRAPH 9527 - Manual (Page 10)

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The view through the collimation cap should now resemble
Figure 9e. A simple star test will indicate how well the tele-
scope optics are collimated.
Star-Testing the Telescope
When it is dark, point the telescope at a bright star and accu-
rately center it in the eyepiece’s field of view. (To achieve
focus with an eyepiece, you will likely have to use the included
35mm extension adapter, as described previously.) Slowly
de-focus the image with the focusing knob. If the telescope is
correctly collimated, the expanding disk should be a perfect
circle
(Figure 14). If the image is unsymmetrical, the scope
is out of collimation. The dark shadow cast by the second-
ary mirror should appear in the very center of the out-of-focus
circle, like the hole in a donut. If the “hole” appears off-center,
the telescope is out of collimation.
If you try the star test and the bright star you have selected is
not accurately centered in the eyepiece, the optics will always
appear out of collimation, even though they may be perfectly
aligned. It is critical to keep the star centered, so over time you
will need to make slight corrections to the telescope’s posi-
tion in order to account for the sky’s apparent motion. Point
the telescope at Polaris (the north star) if you do not have a
mount that tracks.
Care & Maintenance
Give your telescope reasonable care and it will last a lifetime.
When not in use, keep its dust cover on as well as the dust
cap on the eyepiece opening. Store the telescope indoors or
in a dry garage. Do not leave the telescope outside except
when using it. The optical tube has a smooth painted finish
that is fairly scratch-resistant. If a scratch does appear on the
tube, it will not harm the telescope. Smudges on the tube can
be wiped off with a soft cloth and household cleaning fluid.
Cleaning Mirrors
In general, your telescope’s mirrors will only need to be
cleaned very infrequently, if ever. Improper cleaning can
scratch the mirror coatings, so the fewer times you have to
clean the mirrors, the better. Small specks of dust or debris
have virtually no effect on the visual or imaging performance
of the telescope.
The primary mirror and secondary mirror of your telescope
are front-surface aluminized and over-coated with hard silicon
dioxide, which prevents the aluminum from oxidizing.
To clean the secondary mirror, first remove it from the tele-
scope. Do this by keeping the secondary mirror holder sta-
tionary while completely unthreading the Phillips-head screw
in the center hub of the spider vane assembly
(see Figure
12). Do not touch the mirror surface when doing this. Once
Figure 15. To clean the primary mirror, you must remove the
mirror in its cell from the telescope tube. To do so, remove the six
Phillips-head screws that fasten the rear cell to the tube. Then
separate the cell from the tube.
Figure 14. A star test will determine if the telescope’s optics are
properly collimated. A defocused view of a bright star through the
eyepiece should appear as illustrated on the right if the optics are
perfectly collimated. If the circle is unsymmetrical, as illustrated on
the left, the optics need alignment.
Out of collimation Collimated