Light output of fluorescent vs. halogen lights

H

hellboy80

Well-known member
I dont have any experience with fluorescent lights, but I'm planning to buy some. I was wandering how can I compare their light output with halogen lights. I know they are produce much more light than halogen lights, but how much more? Three times, five times? By what number do I need to multiply its wattage?
When I need some equivalent to 300W, 500W, 700W or 1000W halogen lights, how many watts of fluorescent light do I need?

I'm planning to buy something like this (for lighting interviews and maybe short movies), but I have no idea how many watts do I need:
http://www.vect-tech.com/product/18...ge-dsr--h-y4x36-fluorescent-soft-lights-944f/
 
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Well, you can't really compare fluorescents against tungsten/halogen in any really meaningful fashion, unless you're going to always be using your tungsten lights in a softbox.

If you're talking about a softbox, then fluorescent usually puts out about 4x as much light, per watt, as tungsten does. So a 1K tungsten light (1,000 watts) in a softbox, puts out about as much light as a 220w fluorescent lamp in a softbox.

But if you take the softbox off, then the tungsten will put out a gazillion times more light, because fluorescent light has no "throw". You can light up a house across the street with a 1K tungsten PAR, but with a fluorescent the light will dissipate within a few feet.

So it all depends on what you're using it for. If you're talking about interviews (and therefore, presumably, having the tungsten lights in a softbox) then you'd use about 1/4 as much (wattage) in fluorescent to match tungsten.
 
Thanks for explanation.
So what wattage do you think should have fluorescent light ment for shooting interviews (three-point lighting for example)?

Its possible to use fluorescent light as back light? Probably not, right?
 
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Depends on what other light you have to deal with, and also with how sensitive your camera is. On a DVX100, I've lit with a single 55w tube before, and still had to stop the iris down. On an HMC40, I'd want a 4-bank 220w fixture for the key.

You could certainly use a fluorescent for the back light, but it'd be a waste, you'd have to use a pretty strong fluo, whereas you could use a small tungsten fixture.

Another thing to consider with fluos vs. tungsten: if you are trying to match daylight, you need a LOT of tungsten, vs. how much fluorescent you'd need. I said earlier that a 1K in a softbox is about equiv. to a 4-bank 220w fluorescent unit, but -- if you're matching daylight, you'd have to put CTB gel on that tungsten fixture. And that's going to drop the output so far that it would only match a single tube 55w fixture as far as output, because you could get daylight tubes for the fluorescent.

Okay, so that's all the vacillation, so now you want to know what you need? For interviews? Get a 4-bank and a 2-bank and a 250w hairlight and a dimmer, and you should be set for most cases you'll run into.
 
hellboy80 said:
Its possible to use fluorescent light as back light? Probably not, right?
Click to expand...

You can use anything as a backlight as long as it's put in the right position and the distance is right.

In this shot a 4 bank flourescent is backlighting him, about 2 ft. away. Admittedly it's an unusual use for it because of the shorter throw, but in this case it was a small room and a fresnel unit can't be backed away far enough for a large enough spread compared to the flo.

702301959_7wBkA-L.jpg
 
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