Astronomy

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Before getting down to brass tacks on
the settings for a single exposure, there’s
one critical thing to address: Don’t forget to
focus! Focusing nightscapes can be a chal-
lenge because you are working with a wide
field of view and almost no light. Most
autofocusing systems fail in darkness. They
won’t give good results, so turn off autofo-
cus and get good at focusing manually.
Here are two tips for better nighttime
focusing. First, focus your camera in day-
light. Mark the lens with tape where your
infinity focus is sharp. Or, better yet, just
tape the focus ring down. Second, use the
“live view” mode on your camera if it has
one. With live view on, rack your focuser
all the way out to get to rough infinity
focus. Point your camera at a bright star
and then zoom into it. Gently move the
focus in and out until the star becomes as
tight as possible. You can tell when you’ve
reached excellent focus because even the
faint background stars will “pop” into view.
Now you’re ready to take a nightscape.

The best way to start is to go all-in on light

gathering and see your results. From there,

you can experiment with aperture, ISO,

and shutter speed. Start by opening your

shutter all the way. Crank up your ISO —

try 6400 or even higher. Apply the “500

Rule” for your shutter speed: Divide 500 by

your lens’ focal length, and the result is a

decent estimate of how long you can keep

your shutter open before stars will show

trails. Take a few shots. Change your set-

tings. Take some more shots. Don’t be

afraid to experiment; you probably have

plenty of room on your memory card. Test

out all sorts of values. When you get back

to your computer, take the time to evaluate

what works best for your camera and for

your personal taste.

Regarding the computer, I would highly

recommend that you use Adobe Lightroom

for organizing, evaluating, and editing

your images. Keep in mind that all night-

scapes will have some noise, some distor-

tion, and probably a bit of star trailing.

While I won’t cover them now, rest assured

there are advanced techniques, such as

image stacking and focus stacking, that can

dramatically improve the noise signature

and edge-to-edge sharpness in your

nightscapes.

Early on, your goal should be to decide

what is acceptable to you. As you gain more

experience with your artistry, gear, and

techniques, you will begin to intuitively set

up the camera for the type of shot you are

taking. There will be failures; that’s how we

learn. I hope, however, that your initial

triumphs in capturing nightscapes will

keep pushing you to do even better, night

after starlit night.

Steve Cullen is a photographer, videographer,

and photography workshop host. His website is

http://www.stevecullenphotography.com.

This image of star trails includes a perfectly

focused horizon with clouds and automobile

lights. (Sony A7S, Zeiss 25mm Batis lens; f/2.8,

ISO 3200, one hundred twenty 30-second

exposures combined)