ASTRO-PHYSICS Mach1GTO, Руководство пользователя, Страница: 18 / 31

Second, Balance the Polar Axis
1. Now, tighten the D
ECLINATION
C
LUTCH
K
NOBS
and position the mount with the telescope horizontal and the
declination axis horizontal. The C
OUNTERWEIGHT
S
HAFT
is now horizontal with the center of the C
OUNTERWEIGHTS
the same height as the middle of the tube.
2. Loosen the R.A. C
LUTCH
K
NOBS
(also about 2 to 3 turns). Again, be careful because if your scope is significantly un-
balanced, it may swing rapidly in the out-of-balance direction.
3. Move the C
OUNTERWEIGHT
(
S
) up or down to achieve the correct balance in R.A. Again, movement back and forth
about the R.A. axis should have the same feel in both directions.
4. Re-set the tightness of all 6 C
LUTCH
K
NOBS
to the resistance you want making sure that each axis’ 3 clutches are
evenly tightened. (See section on C
LUTCH
K
NOBS
above.)
Try to anticipate any balance problems due to the extra weight of diagonals, heavy eyepieces, finders, solar filters, etc. If the
scope moves by itself, when the clutches are loose, then the scope is not balanced adequately. You may want to “tweak” by
carefully repeating steps 1 – 5 after everything has been attached to the telescope. Be especially careful loosening the Dec.
clutch knobs.
Note: A small amount of imbalance on the East side of the mount is permissible and even desirable for astrophotography
and imaging. This allows gravity to keep the drive train fully engaged while tracking throughout the exposure. If you
intentionally create this small imbalance, you must remember to re-adjust the balance whenever you flip from one side of the
mount to the other. Forgetting to re-adjust can result in a slight see-saw action in tracking that could spoil your next image.
CABLE MANAGEMENT
Introduction to one of the Mach1GTO’s most Innovative Features
In years past, there was no such problem as cable management on astronomical equipment. The only wires or cables would
have been for the clock drive motor of the RA axis, and maybe one for a drive motor attached to the dec’s tangent arm. Today,
we have added the cables that accompany film cameras, CCD cameras, autoguiders, multiple dew heaters, motorized focusers,
and numerous other electronic accessories. Many modern imaging setups have wires going everywhere, and these wires could
be a never ending source of problems and frustrations for the operator. Wires hanging off of cameras can lead to image ruining
flexure. Wires can catch and snag as the mount slews, and were especially vulnerable when a German Equatorial Mount was
“swapping sides” to point at the other side of the meridian. The problem was that all these wires going to all these different
locations had to deal with a mechanical system that was designed to be in motion.
Roland Christen and the design team at Astro-Physics came up with an elegant solution to the “cable nightmare.” If cables all
around the mount are a problem, then run them
through the mount! The idea seems absurdly simple, but it introduced some
significant engineering and design challenges, particularly since this mount is portable and the two axes come apart. Those
challenges were met with the
Mach1GTO . There are four places on the Mach1GTO where cables can enter or exit the inside of
the mount.
1. The first of these is the hub end of the dec axis. Underneath the D
ECLINATION
H
UB
P
LATE
on the end of the declination
axis are two C
ABLE
C
HANNELS
. Cables passing through the hub get routed through one of these channels and on to
their accessory. This is where imaging cables, dew heater cables and motorized focuser cables are most likely to be
routed.
2. The second point of egress is the S
IGHT
H
OLE
/ C
ABLE
A
CCESS
C
OVER
on the dec axis. You can run the dec leg of your
servo drive’s Y-cable out through this opening. It is also a very convenient place from which to feed cables.
3. The third place to run cables in and out is the C
ABLE
A
CCESS
C
OVER
on the RA axis. This is an especially useful place
if you need to do a rough polar alignment each time you set up. It still allows the easy use of the polar scope.
4. Finally, for permanent installations or regular observing spots with marked pier / tripod positions (in other words,
observing sites where you don’t need the polar scope) the cables can be run out the bottom of the RA axis.
Which of these openings you use will depend on your particular situation. All of the openings and internal cable passages have
a two inch diameter clearance that will accommodate a DB15 serial plug with relative ease. It is certainly not required that you
run any cables through the mount, but many of you will find this feature useful.
Preparation
Your approach to cable routing will depend on two main factors: the particular cables you need to run and the degree of
portability of your system. These factors lead to a couple of questions: Will the telescope’s mounting plate remain attached to
the mount between observing sessions? Is the mount often removed from the pier / tripod between sessions? Do you need to
rough polar align each time you set up or can you set up and always be close enough to not need a polar scope? Or are you
17