14
To clean the primary mirror, carefully remove the mirror cell
from the telescope. To do this, you must loosen the three
screws from the end of the optical tube that are flush with
the end of the tube. Completely loosen all three of the flush
screws (do not loosen the other three screws) until the mirror
cell comes out of the telescope.
Now, remove the mirror from the mirror cell by removing
the three mirror clips that secure the mirror in its cell. Use a
Phillips head screwdriver to unthread the mirror clip anchor
screws. Next, hold the mirror by its edge, and remove it from
the mirror cell. Be careful not to touch the aluminized surface
of the mirror with your fingers. Set the mirror on a clean, soft
towel. Fill a clean sink, free of abrasive cleanser, with room-
temperature water, a few drops of liquid dishwashing deter-
gent, and if possible, a capful of rubbing alcohol. Submerge
the mirror (aluminized face up) in the water and let it soak
for several minutes (or hours if it is a very dirty mirror). Wipe
the mirror underwater with clean cotton balls, using extremely
light pressure and stroking in straight lines across the surface.
Use one ball for each wipe across the mirror. Then rinse the
mirror under a stream of lukewarm water. Any particles on the
surface can be swabbed gently with a series of clean cotton
balls, each used just one time. Dry the mirror in a stream of
air (a “blower bulb” works great), or remove any stray drops
of water with the corner of a paper towel. Water will run off a
clean surface. Dry the bottom and the edges with a towel (not
the mirror surface!). Cover the mirror surface with Kleenex,
and leave the entire assembly in a warm area until it is com-
pletely dry before reassembling the telescope.
Figure 12.
A star test will determine if a telescope’s optics are
properly collimated. An unfocused view of a bright star through
the eyepiece should appear as illustrated on right if the optics
are perfectly collimated. If the circle is unsymmetrical, as in the
illustration on left, the telescope needs collimation.
Out of collimation
Collimated
