Sky and Telescope - November 2017 - 63

Out of the Box
Even as I began unpacking the CGX
from its shipping cartons, it was obvious
the mount was designed by people experienced with German equatorial mounts
in the ﬁeld. I had a dozen entries in the
"pros" column of my notes before ﬁnishing the initial assembly. They ranged
from little things like extension marks
on the tripod legs and a locking collar
on the power-input plug, to signiﬁcant
features like ergonomically excellent
lifting handles on the equatorial head
and a tripod design that lets you easily
set the head on the tripod (sans counterweights) and let go without fear of
the head falling off before it's secured
with three cap screws.
Other positive features apparent during the initial assembly included a solid
tripod spreader that also serves as an
eyepiece holder and small accessory tray.
It can be loosened slightly and turned,
allowing the tripod legs to be folded up
without having to entirely remove the
spreader - something I found particularly convenient. The mounting saddle
accepts wide (Losmandy-style) and narrow (Vixen-style) dovetail bars. All the
hand knobs are large, making it easy to
tighten or loosen them. There's only one
size cap screw involved with setting up
the mount, and the corresponding hex
wrench clips into a holder underneath
the carrying handle on the base. But it's
worth noting that the cap screws are
metric, so you'll want to keep track of
them and the hex wrench so they don't
get mixed in with the odd assortment of
English hardware that typically accompanies many observers into the ﬁeld.
Apart from the various electrical
connections on the ﬁ xed part of the
polar-axis housing, wiring for the motor
drives is internal; there are no loose
wires hanging from the mount to snag
as you slew the CGX around the sky.

That's good news, but on the downside
the CGX lacks through-the-mount
wiring for equipment on the mount. As
such, power cables and computer connections for cameras and the like must
be run externally, and that's always
a concern, especially for setups run
remotely. I've had good results using
internal wiring on other mounts, but
Mike Rice, who maintains dozens of
remotely operated telescopes at his New
Mexico Skies Observatory, avoids it. He
says that internal wiring usually adds
extra cables and connections to a setup,
and when problems arise, cables are
often the culprits.
The CGX requires a 12-volt DC
power source capable of delivering
4 amps. It comes with a power cord
having a cigarette-lighter plug but no
AC adapter. An optional adapter ($70)
is available, but I had no problems
running the CGX with a power supply
scavenged from an old laptop. Another
optional accessory I found unnecessary
is the polar-alignment scope ($140),
which attaches to the mount's declination-axis housing. Setting the polar-axis
elevation with the mount's built-in
scale and eyeballing it north was sufﬁcient for visual observing, since the
Go To software in the NexStar+ hand

p The CGX is rated for telescopes up to about
55 pounds. It worked well for astrophotography with this 40-pound setup (that required
an additional 10-pound counterweight) in the
author's backyard observatory. As explained in
the text, the mount was typically run remotely
from his house a few hundred feet away.

control compensates for moderate offset
from the celestial pole once the CGX is
initialized with a star alignment.
The software also has an easy-to-use
method for achieving good polar alignment. The process begins by centering
a selected star in an eyepiece (preferably one with a reticle). The mount
then automatically offsets a calculated
amount from the star, and you manu-

u This 88-minute exposure of the Crescent
Nebula, NGC 6888, in Cygnus was made with
the setup pictured above. It's a stack of 22
consecutive, 4-minute, autoguided exposures
through a hydrogen-alpha filter. The CGX's
smooth tracking and precise response to
commands from the autoguider made every
exposure in the sequence a keeper.
s k y a n d t e l e s c o p e . c o m * N O V E M B E R 2 0 17

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Sky and Telescope - November 2017

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