American Cinematographer - June 2018 - 16

The Ponzo illusion: When two identically sized
parallel lines are placed at different points over
converging lines, they appear to be two
different sizes.

Field Guide
Time Lapse
Celestial cinematography often
involves time-lapse shooting.
Making a successful time-lapse shot
requires an intervalometer - which is simply
a device that counts intervals of time. Many
digital cameras have intervalometer functions built into them, which is very handy. If
you don't already have one in the camera
you're using, you'll have to employ an external one. You can take manual intervals, but
that path creates considerable room for
human error.
In addition to an intervalometer, you
need two crucial pieces of information: the
length of the final shot, and the total time of
the event you're trying to compress into that
final length. Let's say that you're trying to
turn the sunrise into a 10-second shot
onscreen. You've decided that you want the
sun to reach a specific point in the sky for
the end of the shot; using your sun-tracking
app, you determine that the time it will take
for the sun to move from just below the
horizon to that designated point in the sky is
90 minutes.
16

June 2018

ble, as every additional glass element can
introduce more flaring, reflections and aberrations into your image.
Additionally, stopping down a lens
past f8 or f11 will often introduce diffraction elements into the image. The more you
stop down the lens, the more possible it is
that you'll get a starburst diffraction pattern
from the sun, which may or may not be
desirable. A lens with a completely circular
iris will help avoid the starburst effect.
Especially when shooting the sun,
you want your lens to be as clean as possible. Any speck of dust will become visible
when your lens is aimed straight at the sun.
In each situation, day and night,
scouting the location beforehand in normal
daylight is a must. You can see whatever
obstacles might get in your way, and you
can find the right spot where your camera
and your shot will be undisturbed by
people, animals, cars, etc. The tools you will
need on your scout are a compass, a
clinometer, and an app or chart with sun
and moon compass positions and elevations.

Most applications will report a
compass direction and the elevation of the
sun or moon for a given time of day on a
specified date at a particular geographic
location. This information is critical for planning your shot. Apps that I have used
include Chemical Wedding's Helios, Terminal Eleven's SkyView, OzPDA's Sun Seeker
and Crookneck Consulting's The Photographer's Ephemeris. There are many more
available on both Apple and Android
systems, as well as web applications. Even a
plain ol' Google search will tell you the time
of sunrise, and a link or two down you
should find the compass direction where
the sun will appear.
Advanced applications like Sun
Seeker and Helios use the camera in your
phone, allowing you to superimpose the
path of the sun or the moon over the image
so you can visualize exactly where it will be
within a specific composition at a given
time of day. Web pages, books and basic
sun calculators don't know if there's a building or a mountain in your way, or whether
at a certain elevation the sunrise will

That's your starting information:
You're looking to turn 90 minutes into 10
seconds of screen time. Assuming that your
playback is 24 fps, your final 10-second shot
will comprise 240 frames. Ninety minutes
equates to 5,400 seconds; divide 5,400 by
240, and you get 22.5 seconds per frame.
So set your intervalometer to 23 seconds,
and you'll compress 90 minutes of realworld time into a 10-second, 240-frame
shot.
I recommend starting and ending the
time lapse manually unless you have to leave
the camera alone when the sequence will
start and stop. If you start and stop manually, you can begin the roll sooner and end it
later to give yourself some flexibility and
make sure you get the shot you need; you
can always trim the shot down in editing. If
you're unsure about the final duration of the
shot, it's always safer to shoot more frames
than you might need rather than fewer.
Speeding up a shot in post is usually more
successful than slowing one down.
You want to make sure that your
camera is absolutely secure during the timelapse shooting. The slightest movement of
the camera can ruin a shot. I suggest a very

sturdy tripod and head, and sandbagging
the tripod securely in place. Once the timelapse sequence has begun, resist the temptation to approach the camera, as disturbing
the ground around it could cause the
camera to shift, or could kick up dust or
other particulates that could ruin the shot.
Scout your location in the day or days
before the shoot to determine your composition and exposure. Especially if you're
shooting the sun or the moon, you'll need to
know exactly where it will be, what lens you
want to use and what your composition will
be before you arrive for the actual shoot,
when it might be too dark to see. Laser
pointers can be very helpful for adjusting
your composition in the pure darkness; you
can point the laser at an object in the foreground to help you see where that object is
in the dark frame. Maximizing the camera's
ISO and opening up the lens completely can
also help you find your composition - just
don't forget to reset to the ISO and f-stop
that you need for the actual shot once
you've locked the composition.
- JH

American Cinematographer

Table of Contents for the Digital Edition of American Cinematographer - June 2018