Sky & Telescope - September 2019 - 39

SUNSE T: SE A N WA LK ER / S&T

most of the time. Even so, there are ways to minimize the
ship's rocking as well as its omnipresent lights. I often use
ISO speeds of up to 6400 and short exposures of less than
10 seconds to "freeze" the ship's motion as much as I can.
Another way to minimize the rocking of the ship is to shoot
from a lower deck. The rocking motion is more pronounced
the higher up you are, especially at the fore or aft positions.
The closer you are to the center of the ship near the water
level, the smaller these motions are.
Cruise ships are lit up for the safety of the passengers and
crew and to make them visible to other ships and avoid collisions. While this can be very frustrating, there are some spots
on a cruise ship that can work well for night-sky imaging.
Most ships will turn off some lights on the stern late at night,
often where there is a bar or dining area that has closed for

be in the sky in relation to the various areas of the ship. Your
object may be forward, astern (behind), port (left), or starboard (right). The ship may change course, which will change
your sky orientation. It can also be particularly confusing
if you are in a new hemisphere for the ﬁrst time - familiar
sights such as Orion and even the Moon appear upside-down
compared to the view you're familiar with. The entire sky will
even appear to rotate in the opposite direction in relation to
the horizon than what you're used to.
Getting your bearings in the sky is much easier with a
planetarium app that can show you the sky for your particular
location. In your stateroom, the ship's Navigation or Bridge
TV channel may tell you the ship's latitude, longitude, weather
forecast, sunrise, sunset, course, speed, and an overview of the
area where the ship is transiting - all useful information for

p SKY EFFECTS Daytime atmospheric phenomena, such as this bright
sundog seen over Ireland Island in Bermuda, are common sights from
the upper decks.

p CRAZY STARS Most exposures lasting more than a second or two
will show zig-zagging star trails, like this photo of the zodiacal light. Be
sure to take several exposures of each target to ensure at least one acceptable result.

the evening. If you're on a very large vessel where the promenade deck goes completely around the ship including in front
of the bridge, you're in luck. This should be the darkest place
on the ship to allow the bridge ofﬁcers to see unhindered into
the distance. There will be no lights on the bow apart from
the masthead navigation lights and mast lighting will be high
up behind you. Elsewhere on the ship there are lights, so be
sure to use a lens hood and place your camera and tripod
very close to the deck railing. There will be light around you
but the view out to sea that your lens sees will be very dark.
If you get a little lens ﬂare in your exposure, some ship's light
is entering the lens. In these instances, position your body to
act as a light shield for your camera.
The ship's course determines where your astro-object will

planning what to shoot. Input your location in the app, being
mindful of the correct time zone, and you are in business.
When taking your images, try to take lots of exposures
of the same target. Many may be ﬁlled with trailed stars,
but some will inevitably be captured when the ship is brieﬂy
paused between its steady up-and-down motions. Take the
time to assess your results before moving on to your next
composition, and adjust your technique based on the results.
It takes practice, but the results can be quite pleasing, particularly when you consider you are on a moving ship. So fair
winds and following seas, shipmate!

¢ GREG REDFERN is the author of Cruise Ship Astronomy and
Astrophotography, available at https://is.gd/astrocruise.
sk yandtele scope.com * S E P TE M B E R 2 019

https://www.is.gd/astrocruise http://www.skyandtelescope.com

Sky & Telescope - September 2019

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