Sky & Telescope - December 2019 - 69

tp While some might consider f/12 slow for
deep-sky imaging, the 10-inch Cassegrain
made up for its lack of photographic speed by
offering substantial resolution for small, bright
objects. These views of M13 (left) and M27
(above) were each assembled from a stack
of ten 5-minute exposures with a Nikon D700
DSLR camera set to ISO 400.

an astronomy-club meeting with these
images in the '60s, people would have
been ﬂabbergasted. I would have been
ﬂabbergasted too, and to prove that
point to myself I made the images with
a DSLR set to ISO 400 - homage to the
cameras and Kodak Tri-X ﬁlm that was
state of the art back then.

Observing Impressions
This is a hardware review and not an
observing article, so I can't take a lot
of space to wax poetic about the time I
spent observing with the GSO Cassegrain. But it was a lot of fun. On several
sultry nights last summer, armed with
Sky & Telescope's Pocket Sky Atlas, I
tracked down hundreds of targets along
the Milky Way from Sagittarius to
Cassiopeia. My light-polluted sky took
its toll on faint
nebulae, but many
double stars and star
clusters were simply

beautiful at magniﬁcations of about
150×, showing subtle star hues with
unusual purity. Bumping the magniﬁcation up to 305× with a Tele Vue 10-mm
Delos eyepiece made easy work of distinguishing many tiny planetary nebulae
from surrounding stars - something
that isn't as easy using the same eyepiece
on my 12-inch f/5 Dobsonian, because
the magniﬁcation is barely half that of
the 10-inch Cassegrain.
From my backyard observatory
this past summer, Jupiter and Saturn
were only visible as they skimmed the
treetops after dusk when the heat of the
day was still shimmering up from the
foliage. As such, the seeing was poor,
but there were still moments when the
views were excellent. Those and the
success I had observing the Moon in a

higher sky make it clear to me that the
scope is a superb planetary instrument.
For the types of observing and
imaging mentioned above, I can highly
recommend the 10-inch GSO classical
Cassegrain. There are other choices for
wide-ﬁeld observing and astrophotography, but in many respects those instruments can't compete with a Cassegrain
when it comes to the Moon, planets,
double stars, and star clusters that have
been hallmarks of observers for several
hundred years. For these objects a classical Cassegrain really does excel.
■ One reason DENNIS DI CICCO finds
astronomical nostalgia intoxicating is
because observing the night sky remains
every bit as exciting now as it was when
he was a teenager.

u The scope is a superb
instrument visually and
photographically for
the Moon and planets. These images of
Copernicus (left), Gassendi (middle), and the
southern shore of Mare
Humorum with crater
Vitello (right) were made
with a Celestron Skyris
618M video camera at
the scope's f/12 focus.
sk yandtele scope.com * D EC E M B E R 2 019

http://www.skyandtelescope.com

Sky & Telescope - December 2019

Table of Contents for the Digital Edition of Sky & Telescope - December 2019