Sky & Telescope - February 2021 - 56

FEBRUARY 2021 OBSERVING
First Exposure
wavelengths of light emitted by nebulae
and block the majority of light from
artificial light sources.

S Producing colorful images, like this example of IC 348 and the surrounding nebulosity in Perseus, requires patience and a mastery of your equipment. This image was captured remotely using
a Takahashi FSQ-106ED refractor and an FLI ML16803 CCD camera. The exposure totals 16 hours
shot through RGB and hydrogen-alpha filters.

of nebulae and galaxies in mind. This
is the niche known as deep-sky imaging. Typically, a camera - be it a DSLR
or even an imaging device designed
specifically for long-exposure images
- is attached to a telescope in place
of an eyepiece. Photographing faint
nebulosity or distant galaxies usually
requires acquiring sets of long-exposure
frames that are later added together in
a computer using specialized software.
The results can be stunning, revealing

color and detail that's simply impossible
to match visually even with a big scope.
Deep-sky imaging is perhaps the most
challenging astrophotography of all as
it requires precision tracking for hours
on end, which can tax the capabilities of most mounts. But when you get
everything working together, the resulting images can rival (and even surpass)
the quality achieved by professional
astronomers.
But what if your sky conditions
aren't great? Thankfully, some types
of astrophotography are still perfectly
doable. For example, planetary imaging
is essentially impervious to light pollution - the Moon and major planets
are all bright enough to outshine the
background sky. You can even pursue
deep-sky imaging by employing lightpollution filters, or specialized narrowband filters. These pass only the specific
W Imaging the planets doesn't require dark,
country skies. The author captured this detailed
image of Jupiter from Manchester, New Hampshire, with the same telescope and camera
used for the image of Clavius on page 55.

56

FEBRUARY 2 021 * SK Y & TELESCOPE

At a certain point you'll likely need to
get acquainted with image-processing
software and techniques. That's because
there's no good " autoexposure " setting
for night photography. To get the most
out of your images, you have to learn
how to perform post-processing. Understanding the basics of color balance and
what a histogram shows helps inform
your decisions as you convert raw image
data into a presentable astro-portrait.
Indeed, many experienced astrophotographers spend more time working
on their images indoors than they did
acquiring the photos in the first place.
I've briefly touched on the main
types of astronomical photography here,
but each one has numerous subsets
and different approaches to explore.
For example, you might develop an
interest in scientific astrophotography
(like photometry and spectroscopy), or
perhaps in time you'll join the growing
number of astrophotographers who use
remote imaging setups controlled over
the internet. With some of these you
might never see (let alone touch) the
telescopes and cameras used to acquire
your images!
Each category of astronomical imaging comes with its own set of challenges
to surmount. Our goal here is to focus
on those challenges and help you gain
a better understanding of your gear
and its capabilities. We'll still feature
in-depth articles on advanced imaging
techniques elsewhere in the magazine,
but our aim is to use this space to take
some of the steepness out the learning
curve and put you on track to getting
great images of celestial targets.
If you have suggestions for topics you'd like to see covered in
this column, please send a note to
editors@skyandtelescope.org.
„ Sky & Telescope Associate Editor
SEAN WALKER continues to dabble in
every facet of astrophotography from his
home in southern New Hampshire.

NEBUL A E: SE A N WA LK ER / MDW SK Y SURV E Y

Back Indoors



Sky & Telescope - February 2021

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

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Sky & Telescope - February 2021 - Cover1
Sky & Telescope - February 2021 - Cover2
Sky & Telescope - February 2021 - 1
Sky & Telescope - February 2021 - Contents
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