How many watts do I need?

Efexone

Efexone

Well-known member
I need to light a stage with 2 guitarists and a drummer.

I'd like to light the scene using 3 lights, preferably floods...nothing special.

I need enough light to shoot at 1/100 shutter @ f2.8.

I'm looking at 1000W tungsten halogen bulbs, but don't know if they will put out enough light. they gotta cover an area at least 30'x30'.
 
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I'm willing to bet you'll need more than three 1ks for a setup like that, especially for the area you're talking. Either use more lights, or more powerful lights.
 
That all depends on your Asa/Iso but as a reference its always better to have too much light and knock it down than not enough light.
 
I shot a music video a few weekends ago and had to use a 4k to sufficiently light the two guitarists and drummer. That was with the A1 and Letus extreme though.

I would try and get a barger light. I've grown to love the thing as you can go out to as many circuits you want and go up to 6k on household circuits. Pretty sweet.
 
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Mmmm.Barger Bag Lights are awesome. I want one too, they are a pretty killer way of lighting up large areas with soft light without a generator. A DP I work with sometimes owns one. I already have a medium Chimera, just need add a Bag Light.

A very innovative product.

Dan
 
What is the mood of the songs, that may also determine the amount of light that will REALLY require...//Samiul
 
Samiul said:
What is the mood of the songs, that may also determine the amount of light that will REALLY require...//Samiul
Click to expand...

true...

I'm not out to "properly" light em. the music is metal. I plan on lighting it very harshly - sharp shadows, high contrast, but with enough fill to be able to play around in post. the crowd has been scratched out so its just a guitar, bass and drummer on a 1ft stage in the middle of an empty warehouse lit up wit long florescent tubes. its actually pretty bright in there from what i seen but i cant rely on that assumption. I wont color balance the lights to the florescent's either...the lights will be white and the florescents will be nice and green.

I m going to be workin wit one 1k and two - four 500's. distance's between the lights and the band will be close.

ill prob shoot up to 9db gain if i have to.

thx for the help everyone.
 
Efexone said:
I need to light a stage with 2 guitarists and a drummer.

I'd like to light the scene using 3 lights, preferably floods...nothing special.

I need enough light to shoot at 1/100 shutter @ f2.8.

I'm looking at 1000W tungsten halogen bulbs, but don't know if they will put out enough light. they gotta cover an area at least 30'x30'.
Click to expand...


I'm sort of looking for the same answers. Since I'm using a video camera, and will estimate the ISO value at about 320, what 'wattage' do I need in lighting to achieve a given shutter speed, approx 1/48, and f-stop of 5.6 or 8.

The questions that I have is where does one find specific effeciency values for given lights, in particular Lowells.

I looked on the Lowell website and there was no real indication of this sort of specification. I gleened the web and got a sort of 'well halogens are 10-20% better than plain incandecents'... and the the output of a 100 W incandecent is 137 Foot candles (or so...).

And of course, since most lights are in housings, perhaps with reflectors, that changes the calculations because the 'light' is no longer eminating in a sphere...

etc...

Anyway, it would be nice to know with more confidence that one shows up to a shoot with enough wattage to get the shots recorded reasonably well...
 
Foot candle is a measure of light level, not light output, which is measured in lumen. Hence a 100W bulb gives you about 1800-2200 lumen. To get 130 foot candles from a 100W bulb you need to hold it about 1 foot from your object. The foot candle data provided by the manufacturer is always given for a set distance. Double the distance and the light level drops by a factor of 4.

To shoot at 1/48 f 5.6 ASA 320, you need a light level of about 130 foot candles. Since you want high contrast, you probably want your highlights at around 250 foot candles.

A floodlight open face 1K will give you about 200 foot candles at 10 feet. (or 50 foot candles at 20 feet)

A 1K baby fresnel will give you more concentrated light, ca. 150-180 foot candles at 10 feet in flood mode and about 5 times more in spot mode.

Fresnels have angles roughly between 10 and 60 degrees, which means a circle of light between 20" and 70" in diameter from 10 feet away.

Imho, the best stage lights are pars. A 1K par 64 will give you twice as much foot candles as a 1K fresnel at each distance/angle combination, and do so more evenly.

Hope this gives you an idea.
 
capitanfracassa said:
To shoot at 1/48 f 5.6 ASA 320, you need a light level of about 130 foot candles. Since you want high contrast, you probably want your highlights at around 250 foot candles.
Click to expand...


Ok, I found a set of formulas and information on the Lowell lights I plan to use, and have come up with the following chart
of F-stop to Footcandles, referenced to the famouns 18% grey card, required for the given ISO estimate of the DVX100A,
and a Shutter speed of 1/48.


Code: 
Camera:	DVX100A				
ISO Est.	320				
					
Forumula:	Foot Candles = ((fstop^2)/25)*ISO*ShutterSpeed referenced to 18% Grey Card				
					
F-Stop	Adj-f   ND Cor	ISO	Shutter speed	Foot Candles
1.41			320	48	7.5
2			320	48	15
2.83			320	48	30
4			320	48	60
5.66			320	48	120
8			320	48	240
11.31			320	48	480
16			320	48	960
22.63			320	48	1920
32	16	ND 1/8	320	48	3840
45.25	22	ND 1/8	320	48	7680
51.64	16	ND 1/64	320	48	10000
					
					
Light Selection example:					
					
Ligtht:	Lowell V-Light with a 500 W type GDA bulb has the following characteristic at 10' (3 meters).				
	43 fc with doors in 'normal' position				
	25 fc with doors in '180' position				
					
	Hence from the table above I can use an f-stop between F-2.8 and F-4 for the normal position				
	And between F-2 and F-2.8 for the 180 position.


I'll be testing this and report if this actually does do a approximate estimate correctly...
 
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