One of the woes
of location shooting,
small productions when
you can’t afford a generator
or a qualified electrician
to tap into existing
power, is being limited
to wall-socket power in
the 15-amp or, at most,
20-amp variety. This limits you to, at most,
a 2,000-watt fixture (which is definitely
stretching the boundaries of safety).
In the HMI world, you’re limited to a
1,200-watt fixture (or perhaps the Arri
1,800W), if you can afford the HMIs. Fluorescent
figures are a great alternative, but
you’re limited to soft lights and they’re
not necessarily compact or easy to transport.
COMING OF AGE
LEDs came on to the scene several years
ago, but for quite a while they were small
units without much output. Although they
consume much less power than their tungsten
or metal halide cousins, their output
was a fraction of the traditional sources.
Finally, that is starting to change. LED is
coming of age.
|An LED fixture in action. Most LED panel fixtures have hundreds of single LED bulbs in rows that
create soft sources, but can create multiple shadows if they are too close to your subject and they
can be very harsh on talent’s eyes, making them squint.
LED is an acronym for light-emitting
diode. The modern LED was originally invented
in the early 1960s, based on technological
discoveries made at the turn of
the 20th Century. Early LEDs were only
capable of emitting a red light and at very
low intensity, but further advancements
paved the way to brighter red LEDs, then
orange, green and, finally, in the mid 1990s,
the blue LED.
As technology improved, creating
brighter LEDs, techniques were employed
to coat the inside of the plastic lens with
phosphors to turn the bright blue light into
LEDs create light by electroluminescence
in a semiconductor material. This
process happens when an electric current
is passed through the semiconductor and
individual electrons fill “holes” in the material.
These holes are created when an atom
lacks electrons (negatively charged ions)
and, therefore, has a positive charge.
Semiconductor materials such as silicon
can be “doped” to create these electron
holes. Doping (no, not what you’re thinking)
is the addition of elements into the
silicon semiconductor to change its properties.
Doping allows the manufacturer to
create two separate types of semiconductors
in the same crystal—positive and negative—
with a boundary between the two
types called the “p-n junction.” This is why
they’re called diodes, meaning two terminals.
The p-n junction only allows current
to pass through it in one direction. As
electrons move from negative to positive
through the junction, they fall into the
“holes” and emit photons of light.
As blue/white LEDs emit the most practical
light, most LED fixtures are naturally in
the daylight color balance family, although
with phosphor coatings, LEDs can also
match the tungsten spectrum. High-end
LED fixtures manufactured for the photographic
industry are mostly very clean,
with little to no green spike. Consumer
grade or inexpensive LED fixtures often
have a very high green content that needs
to be filtered out.
|Litepanels Sola 6
LEDs require very low power; output
no heat (from the lamp itself); and have
extraordinarily long lamp lives, typically in
the 50,000- to 100,000-hour range. As a result
of this efficiency, many long-term installations
have already switched over to nearly
exclusive LED technology.
In the United States and Canada, all traffic
signals have been switching over to
LED lamps since the mid 1990s. Once the
three primary color LEDs were perfected,
large screens could be manufactured with
red, green and blue diodes clustered together
in “pixel” formations to form pictures,
like a television screen. Many outdoor
giant screens are now made from
LED lamps including Megascreen, D-Lite, Starvision, Monsterscreen and Sony’s massive
These screens go as large as the Adi
iConic 100, a 41-foot x 23-foot LED screen
with a 47-foot widescreen diagonal picture—
it’s an outdoor television larger than
most cinema screens.
The advancements in LED technology
have moved them into the viability range
for film and video applications. Companies
such as Brightline, Litepanels, Kino Flo, Nila,
Element Labs, Zylight and more, are manufacturing
LED fixtures specifically for production.
The typical LED is a 5 mm cylindrical
shape, and although they can come in
larger sizes and rectangular shapes, larger
doesn’t necessarily equal more light. Brightness
from LEDs comes not from size of the
individual diodes, but rather from clustering
many LEDs together.
The LEDs themselves are a fixed color,
generally in a very narrow bandwidth, and
they are not capable of changing color. Film
and video fixtures therefore—just like their
incandescent, gas-discharge or fluorescent
cousins—are available in a specific color
|Looking at the lens and reflector of a multicolored Red, Green and Blue LED fixture from ETC. The
combination of the tri-stimulus arrangement allows the user to create practically any color of the
rainbow by a combination of RGB, but does reduce the intensity possible for any given color.
However, the small size of LEDs allows
for many varying color diodes to be clustered
together and activated at various intensities
to create nearly any color in the
visible spectrum with the possibility of
dimming from one color to the next. This
is the real benefit of LED fixtures—being
able to have both daylight and tungsten in
the same fixture and transition to any approximate
Kelvin temperature in between
by dimming between the two colors.
This nearly negates the necessity of
color correction gel and makes a single,
lightweight and compact fixture, extremely
versatile for many different types of shooting
The real maturity of LED technology is
just starting: Fixtures like the Litepanels
Sola Fresnels, which—despite their enormous
size—can output the intensity and
quality of a tungsten Fresnel at a fraction of the power consumption and heat generation.
Jay Holben is the technical editor of
Digital Video and a contributor to Government
Video. He is also the author of
the book “A Shot in the Dark: A Creative
DIY Guide to Digital Video Lighting on
(Almost) No Budget.”