Astronomy

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partially been reignited
through the work of The World
at Night (TWAN). Initiated by
Babak Tafreshi and Mike
Simmons through Astronomers
Without Borders, the 30 or so
regular TWAN photographers
(and many others) have con-
tributed well-composed images
and time-lapse videos of celes-
tial objects with interesting
natural or human-made land-
marks in the foreground. The
phrases “lightscape imaging”
or “light painting” are often
used to describe such work.

Necessities
What do you need to create
wide-field astronomical images
of your own? First, get a camera
that will allow a number of set-
tings for long-exposure photog-
raphy. I define “long exposure”
here as anything greater than
1 second. The digital single-
lens reflex camera, or DSLR,
is a great choice. Price points
for DSLRs range from several
hundred to thousands of dollars.
And what you may have heard is
true — you can take high-quali-
ty tracked astrophotos with one
of the lower-priced DSLRs.
An alternative to the DSLR
has emerged: the mirrorless
camera. This version doesn’t
need a mechanical mirror to
switch between the viewfinder
and the sensor. Manufacturers
can reduce the camera’s overall
complexity, weight, and size by
replacing the optical viewfinder
with a digital version. This also
eliminates a vibration source in
the system. There are some
pros and cons: Most mirrorless
cameras have reduced-size sen-
sors, require specific mirrorless
camera lenses or a special lens
adapter, and use battery power
at a faster rate than DSLRs.
Sony and Fuji are currently the
leaders in mirrorless cameras.
Like the DSLR, these will con-
tinue to evolve.
Next, invest in a good cam-
era lens. Most of today’s DSLR
lenses easily meet that require-
ment, even those referred to as
kit lenses (less expensive lenses

included with the purchase of a

DSLR). Lens autofocus and

image stabilization features are

not necessary and actually can

cause problems. Your lens focal

length should not be too long. I

usually consider anything lon-

ger than a 135-millimeter tele-

photo lens to be too long,

though I often shoot through

telephoto lenses.

One discussion you might

hear is whether you should use

a zoom lens. Today’s zoom

lenses are much better than

those of 30 years ago, back in

the film era. The glass used to

make lenses is of higher quality,

and the lens mechanics are

greatly improved. I have had

good success using zoom lenses

for astrophotography. With a

zoom lens, I have the f lexibility

to create a specific field of view.

Another advantage is having

multiple focal lengths available

in one lens instead of buying

several fixed-focal-length

lenses. I use both zoom and

fixed lenses for astrophotogra-

phy, yet find myself almost

entirely using zoom lenses for

regular photography.

The effective focal length of

a lens depends on whether you

are using a full-size or cropped-

sensor DSLR. Full-size sensor

cameras (with chips the same

size as the old 35mm film) are

more expensive; the sensor is

larger than the Advanced Photo

System type-C (APS-C)

cropped-sensor cameras.

Because the APS-C camera has

a reduced sensor size, the image

it produces is magnified, thus

reducing your field of view.

Keep that in mind.

Next, let’s take a look at

tracking. A high-quality polar-

aligned mount or go-to plat-

form with accurate tracking is

essential if you want to produce

images without trails.

Accessories are available that

will let you piggyback, or

attach, a camera-lens combina-

tion to a telescope on a mount.

This can be an ideal setup if the

mount is equatorial. The only

drawback to this method is if

you are setting up a scope just

to piggyback a camera, as a lot

of work is involved.

A number of small equato-

rial tracking platforms are

available at reasonable prices.

Each will carry a camera and

lens, or even a small telescope

with a camera attached, but you

will need a sturdy tripod on

which to mount the tracking

platform. Setting up and polar

aligning such a system is usu-

ally easy, and this equipment is

also light, so it’s a joy to trans-

port. For the exposures you’ll

collect, perfect polar alignment

These superb full-frame cameras for astroimaging use different tech. The Canon 6D (right) is a standard DSLR

that employs a mirror to send the image to the viewfinder. The Sony a7R II is a mirrorless digital camera. COURTESY

OF THE MANUFACTURERS

This image of the summer Milky Way was shot through a Canon 6D with

a 47mm lens at ISO 3200. The photographer mounted his camera on a

Celestron Advanced VX tracking mount and made a 2-minute exposure.

JOHN CHUMACK