Sky & Telescope - June 2020 - 68

Electronic Observing

edge-of-ﬁeld optical performance
usually isn't a concern.
There will be times when you'll
want to record video for later study
or to show friends. When I ﬁrst
started, I lugged a VHS recorder into
the ﬁeld, then later switched to a
DVD recorder. Finally, I hit upon the
solution I use now: a small, batterypowered digital video recorder (DVR).
Such devices are available from a
number of sources, including the
retailers who carry the Revolution kit.
Recorded video can be easily transferred to a computer for processing via the SD memory cards
most DVRs use to store imaging data.
One ﬁnal "accessory" that I ﬁnd essential is a Go To telescope mount that will reliably point my telescope at deep-sky
objects. You'll have enough to worry about setting up and
operating the video gear without spending additional time
trying to hunt down and frame faint targets on a small video
chip. Fortunately, since exposures are typically less than 30
seconds long, you don't need a mount with especially accurate tracking, nor is guiding usually necessary.
Unlike conventional astrophotography, one item that's
deﬁnitely optional for video astronomy is a computer. While
some cameras can be controlled by PC or Mac software, most
can also be operated with the buttons on the camera itself, or
an accessory remote control.

Becoming a Video Star
Once you've got your gear, how do you use it? With your
camera mounted to the telescope in prime-focus position
(no eyepiece between the telescope objective and the camera)
and a focal reducer in place if needed, begin by aiming the
scope at a bright star. Take an exposure of 1 second with the
gain/sensitivity of the camera set as high as it will go without
turning the background sky solid white. Even if the scope is

u PICK AND PLAY For those
wanting a more customized
solution, each piece of the
video puzzle can be selected
individually. One popular
component is the MallinCam
Xtreme, a color, cooled, longexposure astro-video camera.
uu IN CONTROL Most astronomical video cameras can be
operated from the camera itself
via a set of buttons or with a
separate remote control, which
makes bringing a computer
into the field strictly optional.

JUNE 2 02 0 * SK Y & TELESCOPE

t GALACTIC WHIRLPOOL Being able to
clearly see the spiral arms in M51 from his
suburban backyard was one of the author's
first video thrills. The frame presented here is
a 10-second exposure.

badly out of focus (which initially it
probably will be) you should see your
star on screen as a big blob. If nothing
is visible, lengthen exposure to 2 or 3
seconds. Once you've acquired your
target, adjust the telescope's focus
until the star is as small as possible.
Then increase the exposure until
dimmer ﬁeld stars become visible and
refocus until they're sharp pinpoints.
Next? The universe is your oyster. I suggest beginning your
video odyssey with the Messier list. No matter how light-polluted your skies, these bright objects will show amazing detail
and will help you get a feel for setting the camera's various
adjustments before moving on to fainter subjects.
When I began using video, I was content with impressing my friends with what the camera could do from so-so
observing sites. Seeing the beautiful spiral arms of M51, the
Whirlpool Galaxy, from my backyard any time I wanted,
took a while to get over. While the experience wasn't quite
the same as observing with an eyepiece, the electronic images
streaming onto my monitor gave me a feeling of immediacy
that conventional astrophotography lacks.
Eventually, it occurred to me that video might be a powerful tool for outreach. I'd long wished I could show visitors
to my astronomy club's public nights the wonders of the sky
beyond just the Moon and bright planets. Unfortunately,
both kids and adults have a hard time seeing any deep-sky
objects in a telescope. Eye placement can be difﬁcult for
anybody unaccustomed to looking into a scope, and dark
adaptation is impossible in the presence of the bright white
ﬂashlights that inevitably show up at such events. I decided
to see if video could help.

Sky & Telescope - June 2020

Table of Contents for the Digital Edition of Sky & Telescope - June 2020