Sky & Telescope - September 2019 - 37

camera to record the night sky. Other models take perfectly pleasing astro-images, and if you desire more pinkish
hydrogen-alpha nebulosity in your images, several vendors
offer affordable services to modify your camera.
Regardless of your camera body, it's the glass (the lens)
that makes the shot. The stars in night-sky photographs are
points of light that excel at revealing the ﬂaws of an inferior
lens, by being distorted into elongated blurs or other strange
shapes. Try to buy quality lenses for your camera - you and
your astrophotos will be glad you did. And since you'll be
shooting at sea where a mist of salty spray might land on
your lens and damage its coatings, pick up a skylight or other
neutral lens ﬁlter to protect its exposed element.
The focal length of the lenses you use depends on what
astronomical object you want to photograph. Wide-angle
lenses in the 18-to-50-mm range, combined with a fullframe camera (or 14-to-35-mm range on an APS-format or
"cropped-frame" camera), will capture excellent vistas that
include several constellations, the Milky Way, or dazzling
aurorae in one shot paired with the glittering sea below.
Longer focal lengths are better suited to capturing bright
subjects, particularly solar eclipses (with a proper solar ﬁlter
during the partial phases) or lunar eclipses.
You'll want to use as fast a lens as you can get, such as f/2.8
or better, in order to take the shortest exposures to minimize
smearing due to the movement of the ship. Be aware that lens
prices get pretty steep on high-quality, fast-focal-ratio lenses,
though you can often ﬁnd good prices on the used market.
The Moon and planets are very small in wide-angle photos, and you really need a long telephoto lens - at least 300
mm - to start to resolve craters. But high-resolution images
of the Moon and planets are better left to your time on land.
After all, you can capture them from virtually any place on
Earth, whereas dark skies often require travelling great distances for many of us.

p VENUS RISING This 8-second exposure recorded through a 35-mm
f/1.4 lens captures the rising central bulge of the Milky Way with bright
Venus reflecting in the waters of a Chilean fjord.

Still, the planets will reveal their respective brightnesses
and colors in wide-angle shots, which can be very beautiful when combined with the Moon or a few constellations
over the open sea. A nifty trick is to photograph the Moon
or planets when they are rising or setting above the sea and
capture their reﬂected light on the water. If you're lucky
enough to have the Milky Way in the frame - well, it doesn't
get much better than that!
Imagers on a limited budget may prefer a multi-purpose
lens to serve both daylight and night photography needs. I
recommend a good 28-to-300-mm zoom lens. These lenses
combine a moderately wide ﬁeld to get those Milky Way
shots, with enough magniﬁcation to pull in details on the

CRUISE SHIP: SE AN WA LK ER / S&T

q OCEAN OBSERVATORY Left: The open ocean is perhaps an unlikely destination for photographing the night sky, but cruise ships can get you to
clear, wide-open skies in a way you may not have considered before. Right: It's often best to avoid shooting from the main deck, where lights from the
recreational facilities overwhelm everything but the Sun and Moon.

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Sky & Telescope - September 2019

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