[opendtv] News: Will LEDs Light Your Productions?
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: OpenDTV Mail List <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 21 Oct 2004 07:35:34 -0400
Could this be the solution for 50/60Hz lighting flicker?
From a Video Systems Newswire...
Will LEDs Light Your Productions?
Dan Ochiva
In Barry Braverman's review of the LitePanels Lighting Kit in
September's Video Systems, the author praised the company's LED-based
on-camera light as an ideal solution for DV'ers. Braverman said the
far more efficient LED device bested tungsten-based gear in
delivering a dimmable, daylight color value along with higher output
than traditional on-camera lights.
There are great benefits, it turns out, if you dump today's tungsten
and halogen lighting technology. Those lamps heat their light
producing metals and gases in such an inefficient way that some refer
to them as heating devices that happen to give off light.
Another strike against tungsten and halogen lights? They need heavy
capacitors and transformers to change AC to DC and filter out the AC
pulses. Such power supplies--which must provide continuous, always on
wattage--are heavy, bulky, and expensive.
But LEDs are different. Light emitting diodes are solid state
electronic devices. They use a pulsed, switching power supply similar
to the one in your computer.
More benefits come from combining an LED and a switched power supply.
A microprocessor, for example, can be used to precisely dim an LED.
LEDs also just keep on working. Some companies claim up to 100,000
hours of useful life for their LEDs, albeit in a laboratory setting.
Those are some of the reasons that make LED-based systems such as
LitePanels such a production breakthrough. But don't think you can
slap one together after a trip to Radio Shack. It's trickier than
that. For example, to achieve the light's useful 80 footcandle (or
lumen) output, a LitePanel is studded with 140 small, carefully
positioned LEDs, with a microprocessor controller onboard too.
This new approach to lighting, says Braverman, enables shooters "to
take control of our craft, and the extraordinary LitePanels system
can help us do precisely that."
But if the benefits are so great, why can't we use LEDs for
production lighting to replace those hot, clunky lights we use today?
Complexity is one reason. Remember, it takes 140 tiny LEDs precisely
fitted into a 6.75 x 2.25-in. form factor to create a LitePanel.
To make a system bright enough to light a set would only result in a
pricey, complex, and fragile light. Heat too becomes a problem with
that many LEDs. While LitePanels' smaller light array doesn't
generate much heat, placing thousands of closely spaced LEDs together
would create enough heat to melt the whole thing.
But a new generation of super bright LEDs will soon change that. One
of the leaders in developing and manufacturing these new LEDs is San
Jose, Calif.-based Lumileds. The company says its Luxeon V Star LEDs
are the most powerful LED light sources available.
How bright? The company says a single Luxeon V Star lights delivers
37 lumens at 1 amp, drawing only 3W of power. (Stats are from the
Lumileds web site.)
Considering that the current LitePanel needs 140 LEDs to deliver 80
lumens...well you can see there's quite a jump in capability. The
Luxeon is specified for AC or DC 12V operation, which means one bulb
can be used in existing low voltage halogen lighting systems.
The brightness of Lumileds' Luxeon opens up new uses. In August, the
company announced that Sony chose Luxeon lamps for its top of the
line Qualia 05 LCD televisions. The lamps, installed in the
Triluminous backlight, replace the fluorescent lighting used by most
LCD displays. The companies worked together to develop a system
suitable for the task, with results claimed to deliver the highest
color gamut. While conventional fluorescent/LCD combinations
reproduce only 65-75% of the NTSC color space, the Qualia 005
delivers a color gamut claimed to be 105% better than the NTSC color
space. (At press time, no one was available to explain that extra 5%.)
A smaller version of the lamp will even turn up in a new generation
of camera phones, due to roll out over these next few months. The two
models deliver either 40 or 80 lumens, said to be 12 times brighter
than standard mobile phone flashes.
Heat, however, becomes a problem when running this new generation of
LEDs en masse. "What heat?" you may ask. But these aren't the
standard sort of LEDs; those are meant to be looked at directly,
which means they don't use much power at all. These pop up
everywhere, in signs, stoplights, and the front panel of your stereo.
However, to light an object, LEDs need to be able to push through
much more power. While the lamp itself is only about 1mm in diameter,
each uses anywhere from 1 to 5 watts. Even a 1 watt LED, if not
properly fitted into a heat sink, gets hot.
In October, Westhampton, New Jersey-based Lamina Ceramics announced a
solution, one which will allow the creation of much larger light
arrays that could be useful in production.
Lamina doesn't make the high-power LEDs itself. Instead, this Sarnoff
Labs spin-off created a method to bond hundreds of LEDs to a single
heat sink. It works, to an extent. Their pioneering disk array design
cuts some of the output of the super bright LEDs, while sucking up
much more energy than expected. The cost is a shocker too: $4900,
though that's not a bad price for fixed installations used in
theaters, for example, which will appreciate the light's long
lifetime.
That 5-in. diameter disk, though, delivers some 13,300 lumens. Wow.
You can get your hands on this new generation of LEDs, but not
immediately. LitePanels has a number of high-brightness lights
nearing design completion. This means that they're on schedule to
release by NAB 2005.
The new on-camera/camcorder light will use only five high-output
LEDs, sourced from another company than Lumileds, says Steve
Gillette, product manager for the LitePanel.
"We're also planning a high-output IR (infra-red) model," says
Gillette. "For general production lighting, expect to see a 12-in. x
12-in. unit that's only about 2-in. thick. You'll be able to
interlock these to create large grids, or mount them on a C-stand."
Gillette promises that the costs will be "affordable" and the heat bearable.
That's a relief. You might soon be able to fire that 'ol quartz lamp,
instead of firing it up.
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