Download 2012 Cave Astrola Telescope Restoration

2012 Cave Astrola Telescope Restoration
Introduced during the middle of the twentieth century, the Cave Astrola Telescope became all the
rage for amateur astronomers and deep sky object enthusiasts during the 1960’s and 70’s. The
Cave Optical Company that was in charge of this minor scientific revolution was led by a father
and son team. Thomas R. Cave, with help from his father,
founded this company and began producing telescope
mirrors, telescopes complete with mountings, and other
Astrola accessories in 1950. The company fluctuated
greatly over nearly two decades, and ended up closing down
in 1979; but not after producing over 80,000 optical mirrors
and 16,000 whole telescopes, and making its mark on
history. After the closing of his company, Cave (Jr.) began
working and producing mirrors for NASA on various
occasions; and is well known for producing the largest
mirror in use at NASA still today. Cave was honored with
many awards in his lifetime, including the Bruce Blair medal
of the Western Amateur Astronomers and the Walter Haas
Award.
Even today, astronomers revere the Cave Astrola Telescope that was introduced by the Cave
family. Even without computerized power, the Astrola is extremely clear and focused, which
allowed for the most optimal sky viewing of its time. This 20th century creation allowed for
many technological advances in astronomy, the telescope itself not being in the least of them.
The makeup of an Astrola consists of one main scope, two to three finder scopes, a mirror,
individual focusers with varying sizes, and lots of miscellaneous parts.
Restoring a Cave Astrola Telescope takes a lot of patience, knowledge, and hard work.
Obviously, this first depends on the condition the telescope is in after these many years. The
Sheridan College Astrola is in fairly decent condition, seeing as though it has been worked on
over the years by multiple astronomy classes and has been kept in a dry, warm place. Dust,
wiring, mounting and realigning are the main challenges here. The Fall 2012 class team found
that the wiring is seemingly destroyed (whether by time, people, or other circumstance is hard to
determine.) Therefore, it was decided that the project will mainly focus on the other three
challenges.
First, cleaning the mirror was a task in itself. Heavy and
susceptible to fingerprints and dust, the mirror must be
cleaned well with water, soap, and special lens cleaning
paper. Many handlers make the mistake of using household
cleaners or cloth towels to clean the surface. This could
leave threads or scratches and could permanently damage the mirror's surface. After the mirror is
cleaned, it will have to be placed in the telescope without being touched on the mirror face itself.
Once this is complete, the next step can commence.
Second, deciding whether or not to create a mount (pedestal) for the telescope is an issue. If the
Astrola was to ever be usable again, especially because of its size and weight, it must be on an
adjustable pedestal that can be moved in altitude and elevation for precise polar alignment.
However, this feat would take welding skills and time. Presenting a blueprint to the welding shop
at Sheridan College is seemingly the only way to complete this, and time is not on our side. A
pedestal, although necessary and beneficial, will probably not be in the reasonable future for this
semester.
The third and arguably most important task would be that of aligning the telescope. With the help
of the Backyard Astronomer's Guide, we first had to
determine how to collimate the telescope. The secondary
mirror was first to be aligned and centered in the focuser. My
partner tightened and loosened the screws on the end of the
telescope that allowed for movement in the mirror;
meanwhile I looked through the eyepiece and tried to
determine if she was turning the right or wrong way. The
difficulty with this was that she was turning and I was trying
to give directions; neither of us had the same left or right. It
would be easier to do as one person, albeit impossible due to the size of this telescope. After
adjusting the secondary mirror, we then adjusted the spider vanes accordingly. (The spider vanes
are used during collimation and are used to control movement of the secondary mirror in
collaboration with the tilt screws.) The primary mirror must then be adjusted in much the same
way. One way to know for certain that the telescope's mirrors are aligned is to place a small
(black or white depending on the light of the area you are working in) dot in the center of the
primary mirror before it is placed in the back of the 'scope. When aligning the telescope, note the
small dot and use it to coordinate the exact center. A light shining in the opposite end of the
telescope proved to be helpful. After the above is complete, the telescope should be in decent
alignment.
Star testing is the ideal way to assume the alignment is correct. Without the mount and pedestal
available for the Cave Astrola, our group had to use a “fake” star point created by a pinhole of
incandescent light similar to that of a natural star’s light angle. This we performed by setting up
that light at the end of the hall, and attempting to adjust the height, angle and positions right to
left of the telescope at the opposite end. This proved difficult due to the manual lifting and
positioning of the Astrola on the floor. In the end, we succeeded with a decent visual of the
mirrors aligned and the picture clear.
Thomas Cave and his father made their mark in
scientific history by creating this telescope. My
partner and I tried to make our mark on the Sheridan
College Astronomy program by attempting to restore
a 1960's Cave Astrola Telescope. While we may or
may not completely finish this scientific feat this
semester, we have learned so much about astronomy,
Cave Astrola Telescopes, and mechanics that it made
the experience all worth it.