http://www.skyandtelescope.com.au 69The back end
of the Trius
includes a 6-pin
RJ-12 autoguider
port, a USB 2.0
port to connect
the camera to
your laptop, and
a 3-port USB
mini hub that
enables users to
connect up to
three additional
accessories,
including a
filter wheel, an
autoguider camera
or the company’s
Active Optics
guiding unit.The Trius includes an assortment of cables for use with the
camera’s internal USB mini hub, and an autoguider cable for
using the SX-814C as a guide camera. A unique ‘Y’ coax splitter
powers both the camera and its external cooling fan.There’s an external cooling fan that supplements the
unit’s regulated thermoelectric cooling (TEC). Its
CCD chamber is sealed with a fused silica window
and purged with argon to prevent condensation from
forming on the cooled chip.
One particularly nice feature of the Trius design
is an integrated 3-port USB 2.0 hub at the rear of
the camera. This helps reduce the number of cables
connected to your host computer. I took advantage
of the hub to connect a Lodestar X2 autoguider and
a filter wheel so that only a single USB 2.0 cable ran
from the camera assembly to my laptop. The camera
is powered by 12 volts DC and includes a universal AC
adapter. A ‘Y’ coax power cable feeds the camera and
exterior cooling fan. The camera can function as an
autoguider and includes a 6-pin port to interface with
your telescope mount.
Both cameras come with the control software
SXV_HCOL _USB, which provides all the necessary
functions of image acquisition, as well as post-
processing functions such as calibration and stacking.
While it functions adequately, it is proprietary to the
Trius and will not, for example, open FITS images
acquired with the camera using other software.
Starlight Xpress also recommends Stark Labs
Nebulosity 4 (stark-labs.com), and MaxIm DL (cyanogen.
com). I tried each during my testing, though I preferred
the latter two as I have more experience with them
Mini Filter Wheel and Lodestar X2
Whether you’re a fan of monochrome or one-shot
colour cameras, a good autoguider is an essential
accessory when shooting deep sky targets, and the
Lodestar X2 autoguider didn’t disappoint.
Like the Trius, the Lodestar X2’s highly sensitive
monochrome Sony ICX829 CCD detector produces
extremely low-noise images, which permitted me to
easily locate suitable guide stars with exposures of two
seconds or less on all the instruments I paired it with.
Like the Trius, the guider doesn’t have a shutter. Its
752 × 580 pixel array measures 6.47 × 4.81 mm.
The Lodestar X2 has a versatile, compact design
that can be used with most any guidescope or off-axis
guider. The camera’s outside diameter is precisely 1¼
inches, which fits in any standard telescope focuser.
Furthermore, the front aperture includes C-mount
threads, permitting a rigid connection to the off-axis
guider (OAG) built into the Starlight Xpress Mini Filter
Wheel that I tested. While a filter wheel isn’t a necessary
component when paired with a colour camera, it is
useful for shooting with specialised filters that block
light pollution. The filter wheel can also function as a
mechanical shutter; more on this in a moment.
The Lodestar X2 C-mount threads are convenient
for attaching the guider to conventional camera lenses
with standard C-mount adapters, thus creating an
effective, freestanding autoguider and imaging setup.
Power for the Lodestar X2 comes from its USB 2.0
connection to the host computer (or Trius hub),
and an RJ-12 cable is supplied to interface the
guider with your mount. One note of caution
here: the pin-out arrangement for the
guiding interface cable is wired opposite
to what has become the de facto standard
on most telescope mounts, so it’s important
to use the RJ-12 cable supplied with the
Lodestar. Other ST-4 compatible cables won’t
work with Lodestar X2. This is a touch ironic
since the Lodestar cable is actually wired the same
as the RJ-12 cables that have long been a standard
in the telephone industry — it is the ST-4 cables that
are different despite their now wide acceptance in the
telescope world.
A small LED on the rear of the Lodestar housing
lights up green when the guider is powered up and
briefly blinks red when sending guiding corrections to
your telescope mount.
The effectiveness of the Lodestar X2 is best
described by the ease with which I located guide stars
with the filter wheel’s OAG. The Starlight XpressWHAT WE LIKE:
Extremely low-noise images
Easy to useWHAT WE DON’T LIKE:
No mechanical shutter