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lawpoop
Guest
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 Posted:
Tue Nov 22, 2005 1:36 am Post subject:
Large LED bulbs for film lighting? |
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Hey folks -
I'm just getting into amatuer filmmaking. I took a class on low budget
lighting and we spent a great deal of time talking about scouting
locations properly for lighting. Two things you really have to worry
about are power draw and heat. With movie lighting, it's easy to blow
the circuits because several 1000 watt bulbs draw a lot of power, and
then also they create a lot of heat. This makes it easy for them to
melt plastic filters, their housing, even blow up the bulbs themselves.
That's why you hear the director call "Lights! Camera! Action!" --
because the lights are shutdown between takes to cool off.
Of course, most of these problems are caused by the fact that these are
incandescent bulbs, which waste a lot of energy as heat. A lot of these
problems could be sovled by more effecient lighting techniques -- say
LED bulbs.
I know that LED bulbs are just now getting into home lighting, but I
wonder why they aren't used in more film lighting. Film lights are
expensive anyway, so I would guess LED lights could compete more
effectively than in the home.
Why are LEDs so small?
Is it possible to get an LED bulb that kicks out 1000 watts of light,
yet leave a small current and heat footprint?
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Andy Baxter
Guest
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| Posted:
Tue Nov 22, 2005 1:36 am Post subject:
Re: Large LED bulbs for film lighting? |
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lawpoop said:
| Quote: | Hey folks -
I'm just getting into amatuer filmmaking. I took a class on low budget
lighting and we spent a great deal of time talking about scouting
locations properly for lighting. Two things you really have to worry
about are power draw and heat. With movie lighting, it's easy to blow
the circuits because several 1000 watt bulbs draw a lot of power, and
then also they create a lot of heat. This makes it easy for them to
melt plastic filters, their housing, even blow up the bulbs themselves.
That's why you hear the director call "Lights! Camera! Action!" --
because the lights are shutdown between takes to cool off.
....
Is it possible to get an LED bulb that kicks out 1000 watts of light,
yet leave a small current and heat footprint?
|
http://www.publicscreen.co.uk/net/index.html
do multicoloured LED spotlights.
--
http://www.niftybits.ukfsn.org/
remove 'n-u-l-l' to email me. html mail or attachments will go in the spam
bin unless notified with [html] or [attachment] in the subject line. |
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Andy Baxter
Guest
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| Posted:
Tue Nov 22, 2005 1:36 am Post subject:
Re: Large LED bulbs for film lighting? |
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Andy Baxter said:
| Quote: | lawpoop said:
Hey folks -
I'm just getting into amatuer filmmaking. I took a class on low budget
lighting and we spent a great deal of time talking about scouting
locations properly for lighting. Two things you really have to worry
about are power draw and heat. With movie lighting, it's easy to blow
the circuits because several 1000 watt bulbs draw a lot of power, and
then also they create a lot of heat. This makes it easy for them to
melt plastic filters, their housing, even blow up the bulbs themselves.
That's why you hear the director call "Lights! Camera! Action!" --
because the lights are shutdown between takes to cool off.
...
Is it possible to get an LED bulb that kicks out 1000 watts of light,
yet leave a small current and heat footprint?
http://www.publicscreen.co.uk/net/index.html
do multicoloured LED spotlights.
|
P.S. they aren't on their site, but this was reported in the Sep 2003
issue of electronics world, so maybe they still do them, or know someone
who does.
--
http://www.niftybits.ukfsn.org/
remove 'n-u-l-l' to email me. html mail or attachments will go in the spam
bin unless notified with [html] or [attachment] in the subject line.
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John Popelish
Guest
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| Posted:
Wed Nov 23, 2005 1:35 am Post subject:
Re: Large LED bulbs for film lighting? |
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Bill Bowden wrote:
| Quote: | I don't think you can get as good a white color with LEDs as with
incandescents. White LEDs tend to be on the blueish side.
(snip) |
Most white LEDs are really blue LEDs thinly coated with a phosphor
that absorbs blue light and emits yellow. The combination of blue
(that gets past the phosphor) and yellow fool the eye into seeing
roughly white. But there are big chunks of the visible spectrum
missing, specifically green and red. So green or red objects (things
that absorb blue and yellow, but reflect green or red light) look off
color and dim when illuminated by white LEDs. |
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Bill Bowden
Guest
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| Posted:
Wed Nov 23, 2005 1:35 am Post subject:
Re: Large LED bulbs for film lighting? |
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| Quote: | I know that LED bulbs are just now getting into home lighting, but I
wonder why they aren't used in more film lighting. Film lights are
expensive anyway, so I would guess LED lights could compete more
effectively than in the home.
|
I don't think you can get as good a white color with LEDs as with
incandescents. White LEDs tend to be on the blueish side.
Also, LEDs are less efficient than incandescents if operated at full
power. To beat the efficiency of incandescents, I believe you need to
reduce the power level quite a bit and add more LEDs to make up for the
lost light.
-Bill |
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Don Klipstein
Guest
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| Posted:
Mon Nov 28, 2005 11:58 pm Post subject:
Re: Large LED bulbs for film lighting? |
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In <1132613969.913567.88380@z14g2000cwz.googlegroups.com>, lawpoop wrote:
| Quote: |
I'm just getting into amatuer filmmaking. I took a class on low budget
lighting and we spent a great deal of time talking about scouting
locations properly for lighting. Two things you really have to worry
about are power draw and heat. With movie lighting, it's easy to blow
the circuits because several 1000 watt bulbs draw a lot of power, and
then also they create a lot of heat. This makes it easy for them to
melt plastic filters, their housing, even blow up the bulbs themselves.
That's why you hear the director call "Lights! Camera! Action!" --
because the lights are shutdown between takes to cool off.
Of course, most of these problems are caused by the fact that these are
incandescent bulbs, which waste a lot of energy as heat. A lot of these
problems could be sovled by more effecient lighting techniques -- say
LED bulbs.
I know that LED bulbs are just now getting into home lighting, but I
wonder why they aren't used in more film lighting. Film lights are
expensive anyway, so I would guess LED lights could compete more
effectively than in the home.
Why are LEDs so small?
Is it possible to get an LED bulb that kicks out 1000 watts of light,
yet leave a small current and heat footprint?
|
As it turns out, a 1,000 watt incandescent puts out about 90-100 watts
of light, maybe 500-600 watts of infrared and 300-400 or so watts of
non-radiant heat (roughly).
1,000 watts dumped into the most efficient LEDs out there, with those
LEDs being run at full power, may get you 150 watts of visible light, not
much infrared, and almost 850 watts on non-radiant heat (roughly).
The ratio of heat to light actually increases due to lack of getting rid
of heat as infrared. Just to make things worse, LEDs are less tolerant of
high temperatures than incandescents.
So, heat issues in fixtures are a reason to use incandescent lamps
(including halogen lamps) over LED.
But the main reason is that high power LEDs and high power LED cluster
lamps are expensive. A 5-watt LED in small quantities costs around $30,
give-or-take.
There are LED stage and filming lights, but they are not yet in really
widespread use.
Advantages of LED stage and filming lights in general are, at least
theoretically:
1. Ability to achieve some shades of colored light more efficiently than
with incandescents and filters
2. Ability to change color electrically
3. Strobing capabilities that incandescents don't have
But for high efficieny of producing light for filming, what they tend
to use is special metal halide lamps such as HMI and the like.
- Don Klipstein (don@misty.com) |
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