Sky & Telescope - December 2021 - 71

To be fair, the MSM is advertised
first and foremost as a portable nightscape
tool, for use with more forgiving
wide-angle lenses. Using a 24-mm
lens and the MSM mounted on its
back, I made sets of 1- and 2-minute
exposures. The resulting yield was better,
with only 20% to 30% of frames
trailed to some extent. Some of the bad
frames were at the start of a sequence,
when the MSM's gears sometimes took
a few minutes to engage and begin
tracking.
By comparison, in two sets of 40
pThe laser, once collimated, proved accurate,
though it may not be legal to own or operate in
some countries. Here it's shown aimed at the
north celestial pole, just above Polaris on this
spring night. The optional phone mount with
the author's smartphone running the PhotoPills
app also proved a coarse but reliable method
of polar alignment.
85-mm lens and the camera aimed east,
south, and west, I found the failure rate
(the percentage of unacceptably trailed
images) to lie between 15% and 60%.
Sometimes the MSM tracked very well;
often it did not. There was no consistent
pattern, though the ratio of good-to-bad
frames seemed better with the MSM
mounted on its back (as seen at top of
facing page) rather than on its side.
Using 135-mm and 200-mm lenses
(both of which fall within the advertised
limits for focal length and weight
for the MSM), I found the failure rate
of trailed frames in 60- to 90-second
exposures to be as high as 75%.
I wouldn't recommend the MSM for
anyone with ambitions to shoot deepsky
objects.
2-minute exposures with the same
24-mm lens and camera on the SkyWatcher
Star Adventurer Mini (one of
the MSM's closest competitors), every
frame was usable. (See the December
2017 issue, page 58, for my review of
the Sky-Watcher tracker.)
Time-Lapse Functions
As noted earlier, the Move-Shoot-Move
tracker's namesake feature is its timelapse
mode. This feature allows users to
shoot a sequence of still images that are
later assembled into movies in which
the camera pans slowly across a scene
while the foreground and sky change
over time.
For shooting time lapses, the MSM is
mounted horizontally on its other large
surface, so its rotating circular platform
attaches to a tripod, with the main body
of the MSM on top, to turn with the
camera. What's now the top surface has
a bubble level and arrows showing which
way the MSM will turn when set to the
North or South direction. These tend to
baffle some users but serve a valuable
purpose in the time-lapse configuration.
pThe Alyn Wallace V plate allows the camera to
be turned by hand from frame to frame parallel
to the horizon while the MSM tracks the sky, allowing
for tracked nightscape panoramas.
The hot-shoe-to-rotator cord is
necessary in time-lapse mode to send a
signal to the MSM drive that initiates
movement after each exposure.
When shooting time lapses, the
MSM turns by a tiny increment
between each frame when the shutter
is closed. It shoots, moves, then shoots,
moves, etc. This prevents the ground
from blurring during long exposures
at night. How much the MSM moves
between each shot is governed by the
four hard-wired speeds selectable on
its backlit control panel. In all, the
MSM worked quite well for time lapses,
serving as a low-cost unit for someone
getting started.
A sample 4K video of test time lapses,
along with my written tutorial on how
to calculate time-lapse sequences with
the MSM, is available at vimeo.com/
theamazingsky/msmtest.
sk yand tele scope .o r g * DECEMBER 2021 71
http://www.vimeo.com/theamazingsky/msmtests http://www.vimeo.com/theamazingsky/msmtests http://Skyandtelescope.org
Sky & Telescope - December 2021

Table of Contents for the Digital Edition of Sky & Telescope - December 2021
