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My 8-inch
dobsonian was built during the summer of 1998. The base and
rocker box is constructed of 3/4" plywood, the tube is a 10-inch
"QuikTube" cardboard concrete form (similar to "SonoTube" but denser,
stronger and not as thick). Some PVC pipe ends serve as altitude bearings.
The optics are purchased parts - the mirror set is from Murhnigan
Instruments, the focuser is from Orion Telescope Center, the diagonal mirror
holder, teflon bearing pads and Telrad finder came from Astrosystems. |
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First Place at RMSS 2000!
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I built an equatorial platform based upon Chuck Shaw's cylindrical bearing
equatorial. If you are new to astronomy,
the Earth's rotation causes the stars to "move" in the sky. Since the view
in a telescope is greatly magnified, this motion is also magnified and
therefore a star or planet you are viewing quickly moves out of view. An
equatorial platform is designed to track the movement, keeping the star or
planet centered in your eyepiece.
The platform is constructed of 3/4" plywood, sliding shower
door rollers, 1/4" screw rod, and a few pieces of aluminum from a local
hardware store. A gear motor from Jameco
Electronics
, a voltage regulator, potentiometer from Radio Shack, and
some model car drive gears from a local hobby shop completed this project.
I later added a leaf switch and a sonic alert so I know when the
platform has reached the end of its motion.
The drive mechanism is my own design, and
is completely linear (no speed increases near the ends of travel) This
project helped me earn First Place
in the Amateur Telescope Making competition at the Rocky Mountain Star
Stare in June of 2000! I won a certificate and a copy of SkyMap Pro 6 (a
very nice astronomy software package). |
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I made some simple modifications to my Celestron NexStar 5 .
Initial star alignment can be a bit of a pain on many computerized scopes,
the NexStar is no exception!
I purchased a
couple of stick-on bubble levels from a local building center.
One level was added to the battery cover in center
of the base and the other one was added to the "top" of
the telescope tube.
Once I open
the tripod, the
round bubble level on the base makes it a snap to level the entire scope.
I then rotate the telescope tube until it is level before I begin
the 2-star alignment. Alignment is now a snap and I spend more of my time
observing!
Another
modification (not shown) involves the external power cord. Sometimes when the NexStar was seeking to
an object, it would pull the power cord out of its socket (there
went my nice star alignment!). I added a small stick-on cable clip which holds
the cable nicely in place. No more power outages in the middle of
observing. |
Under
Construction...
Photo coming
soon! |
Awhile ago I received a SuperCircuits
PC164C video camera as a gift. These little
cameras have very low light capabilities which should make it useful for
astronomical work. However, the cameras automatic gain control tends
to run wide open when mounted on a telescope. For planetary photography, this
is a huge annoyance as it causes serious overexposure and all you
capture is a big white
blob.
Some members of Yahoo's VideoAstronomy
group have worked out gain control modifications
for the PC164C. A thank you goes to Scott McCluney of the
VideoAstro group for providing information which I used
to modify my PC164C.
This project is currently under
construction. Please check back later, an update will be posted here
shortly!
Yahoo's VideoAstronomy group also maintains a VideoAstro
web site with general information
and tips about using video cameras and webcams for
astronomy... |
