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Pro Secrets:
How to Photograph a
Rainbow
by
Ian Plant
Who doesn't love
rainbows? Rainbows are a favorite of nature
photographers, and for good reason. Not only are
they beautifully vibrant, representing all colors in
the spectrum that can be seen by human eyes, but
their graceful arcing shapes add compositional
interest to photographs.
But finding rainbows
is a tough business, and doing them justice even
tougher. So, what is the best way to photograph a
rainbow? This tutorial contains a few tips to
optimize your chances of getting great rainbow
photos.
A
brilliant rainbow over a dwarf forest, Los Glaciares
National Park, Argentina
(Patagonia).
What
is a rainbow?
A
rainbow is a meteorological phenomenon that causes a
spectrum of light to appear in the sky when the sun
shines onto droplets of moisture in the atmosphere.
Rainbows take the form of a multicolored arc, with
red on the outer part of the arc and violet on the
inner section of the arc. A rainbow that forms at
sunrise or sunset will often look more red than
multicolored.
Sometimes, a dim secondary rainbow is seen outside
the primary bow. Known as a "double rainbow," such
secondary rainbows are caused by a double reflection
of sunlight inside the raindrops. Because it is a
second reflection, the colors of a secondary rainbow
are inverted compared to the primary bow, with blue
on the outside and red on the inside. Although I've
never seen it happen myself, old timers often spin
yarns of seeing a rainbow reflected two or three
times in the sky. Multiple rainbows are rare, but
they do happen—if
you see one, shoot first and ask questions later!
A
double rainbow forms in the Colorado mountains.
How
to find a rainbow
Rainbows need two key ingredients: moisture in the
atmosphere, and sunlight. Your best chances of
seeing a rainbow are during or right after a
rainstorm. You don't need to get rained on to see a
rainbow (although it certainly doesn't hurt your
chances)—as
long as there is rain falling nearby, you might see
a rainbow.
Conditions most conducive to rainbow formation are a
period of rain followed by sudden clearing in the
direction of the sun. If sunlight breaks through the
clouds while there is still significant moisture in
the sky, a rainbow might form. Rainbows always form
in the sky opposite the sun's position.
How
to photograph a rainbow
When photographing rainbows, you basically have two
options: photograph just the rainbow, or make the
rainbow an element of your overall composition. If
you choose the first option, a telephoto zoom lens
may be your best choice, allowing you to get in
close. If you choose to include the rainbow as a
part of your overall composition, a wide-angle zoom
lens is best.
Everyone knows that the endpoints of a rainbow
(where the rainbow terminates at the horizon) are
great places to find leprechauns with their pots of
gold. More relevant to this discussion and to
reality, the endpoints of a rainbow are also places
of compositional power and interest. Make sure to
include at least one endpoint in your composition.
You will need a very wide-angle lens to be able to
include both endpoints and the entire arc of the
rainbow simultaneously.
It is
best to photograph a rainbow against an uncluttered
and dark background, if possible. Gloomy storm
clouds and dark mountain peaks make great
backgrounds. If working with a wide angle lens, look
for an interesting foreground to add to the
composition. Ideally, the shapes of foreground
elements should somehow relate or lead to the
rainbow itself. If you include foreground elements
that are close to the camera, you may need to select
a small aperture (f/16 or f/22) to ensure that you
have sharp focus throughout the picture.
A 14mm
lens was used to capture the entire arc of a sunset
rainbow over Big Stone Beach, Delaware Bay.
Your
choice in composition when photographing a rainbow
often depends on how much of the rainbow you can
see. Often, only part of the rainbow will be
visible. If you are lucky, you will see the entire
arc of a rainbow. If you can include the entire arc
in your photograph, centering the rainbow is
appropriate, although consider placing the rainbow
and the horizon in the upper third of the image
frame. If you can see only a portion of the rainbow,
consider placing the rainbow's endpoint in either
the left or right side of the picture, away from the
center. Having the rainbow arc into the scene is
typically better than having it arc out.
Rainbows vary in intensity. Faint rainbows will not
show up all that well in photographs. When you see a
rainbow, no matter how faint, start shooting—a
rainbow may start off weak, but increase in color
and intensity over time. Make sure that you take as
many photos as possible during peak intensity!
A
polarizer filter can help bring out the colors of
the rainbow. But, you ask, aren’t polarizer filters
supposed to remove reflections? Aren’t rainbows
reflections in the sky? Although both are more or
less true (a rainbow is really more refraction than
reflection), if
you polarize only slightly, you can actually
intensify the colors in the rainbow, rather than
remove them. Experiment with the polarizer, turning
the filter until you get the desired result. Avoid
full polarization, as it may remove the rainbow from
the sky.
Although I tell my students to always use a
tripod for nature photography, this holds doubly
true for rainbows. Rainbows often form during stormy
periods with low light, and if you are using a
polarizer filter and a small aperture for
depth-of-field, your exposures will likely be too
long for hand held photography. A tripod is a must
if you want sharp images.
Spray
rainbows
Rainbows
can also form in the spray of waterfalls and ocean
surf. As with sky rainbows, spray rainbows only form
when sunlight is shining. However, they are more
predicable than sky rainbows, as rain is not
necessary for them to form—they
have their very own steady source of moisture.
Look
for spray rainbows at the base of waterfalls with
relatively open exposure to the sky when the sun is
shining high during mid-day. Because you are working
with mid-day light, be aware that you will likely
encounter a significant amount of contrast between
sunlit and shadowed portions of the scene. Expose
carefully to ensure that your highlights are not
overexposed, letting shadows turn to pure black if
necessary. Consider isolating portions of the scene
to avoid areas of excessive contrast.
A
rainbow forming in the spray at the base of a
waterfall on a sunny day.
When
working on the shore, look for spray rainbows on
days when the surf is extra choppy. Heavy and gusty
winds will often lift spray off of the crests of
incoming waves, and if you have the sun at your
back, you will see spray rainbows. A telephoto lens
will allow you to get in close to the action. These
rainbows are very short-lived; select a continuous
shooting mode and fire off a quick burst of shots
whenever you see a spray rainbow form.
Spray
rainbows forming in the surf are short-lived—shoot
fast!
Related phenomena: moonbows and halos
A
moonbow is essentially a rainbow that forms at
night by moonlight instead of sunlight. All of the
above tips apply when photographing moonbows, but
exposure times will often be several minutes long.
Since the moon is much less bright than the sun,
moonbows are difficult to see. Not unlike rainbows,
moonbows always form opposite the moon. Although to
the human eye a moonbow appears white, moonbows in
fact have all the colors of a rainbow, and they will
show up in a long exposure photograph. Moonbows are
easiest to see when the moon is full.
A
halo is an optical phenomenon similar to a
rainbow, but instead of resulting from rain, it is
produced by ice crystals. Halos take the form of
white arcs in the sky. The mostly appear around the
sun or moon. Since they often lack color, they make
great black & white subjects.
A halo
forms over the Fitz Roy massif, Los Glaciares
National Park, Argentina (Patagonia).
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