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lights or dimmers?

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Ty Ford
lights or dimmers?
on Apr 11, 2007 at 12:13:18 pm

Hi,

I use a Mole Richardson biax-4 for a key light and have recently been given two fixtures with 650 W lamps. They're great but 650 is a lot of light. Is it better to get smaller lights or dimmers? If dimmers, which ones?

Thanks,

Ty Ford

Ty Ford's "Audio Bootcamp Field Guide" was written for video people who want better audio. Find out more at http://home.comcast.net/~tyreeford/AudioBootcamp.html
or http://www.tyford.com
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Bob Cole
Re: lights or dimmers?
on Apr 12, 2007 at 3:37:23 am

[Ty Ford] "two fixtures with 650 W lamps"

Try:
lower wattage bulbs
scrims
diffusion
place lights further away

Dimmers on tungsten fixtures can be a problem, in my experience. In very quiet settings where I have to record people talking, dimmers can create a buzz on the sound track. I think my "Magic Gadgets" dimmers are well-made, but the dimmed tungsten filaments can generate a buzz on the sound track, even if I run the camera and audio on batteries and am religious about not crossing mic and power cables.

-- Bob C


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Dennis Size
Re: lights or dimmers?
on Apr 13, 2007 at 3:54:47 am

Are these open-face tungsten fixtures?

DS


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Dennis Size
Re: lights or dimmers?
on Apr 13, 2007 at 3:53:16 am

My philosophy: I can always make my light less intense (via dimmers, scrims, Chimeras/silks, screens, etc.) but when I need more light I can't get a 500w fixture to deliver the output of a 1000w one.


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P. J. in Hollywood
Re: lights or dimmers?
on Apr 13, 2007 at 6:28:43 am

Dimmers present several problems for the videographer when using tungsten lights. First, when you use dimmers, you also drop the color temperature. Now you have mixed color sources that are difficult to control or repeat. If you shoot out of sequence, you'll have continuity problems. Best to use scrims and gels if you want to warm it up a bit or cool it down a bit. You can always color correct in post, but that takes more time and money. Light it right the first time.

Household dimmers get hot as they are resistance type dimmers. They are not intended for use with movie lights. SCR dimmers are expensive and can buzz. Dimmers are only generally useful with events, but not used much in features or commercials. In music videos, anything goes.

650 watts is actually not much light by the time you add diffusion. Unless you want a specular pinpoint light, you'll diffuse your light probably by one to two stops.

If you're only doing interviews, you don't need much light. Add one person, double the amount of light needed. Now person A's key is person B's fill. You'll need 1/2 scrims to even out the intensity.One kicker for A and one for B. Light the background separately and you'll have some depth to your image.

Also HDV requires more light than DV. Additionally, remember the inverse square law. Light intensity diminishes inversely to the square of the distance increased. Double the distance of your light, and you drop the light intensity of the light by the inverse square of the increased distance. e.g.

Sounds like you might benefit by studying some lighting basics. Check your local library or book store for books on motion picture lighting.
A lack of basic knowledge of your craft will hold you back and make your efforts less than professional. Lighting takes study and practice.

A good start would be "Motion Picture and Video Lighting" by Blain Brown, published by Focal Press. If you want to know about the different equipment that is used, try "Set Lighting Technician's Handbook" by Harry C. Box, also published by Focal Press.

Hope this helps.

PJ






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Bill @ UGA
Re: lights or dimmers?
on Apr 26, 2007 at 5:12:34 pm

Hello, Ty

Lots of good advice here, but I'd like to add one more thing that works well. Invest in some neutral density gel, which is a smoky-colored gel available in different degrees of light-stopping "thicknesses." This gel will knock out the intensity of your light without changing the color temperature. It's cheap, light to carry, and available lots of places. You can cut to size to fit each light's gel frame or simply clamp a sheet to the barn doors. Worth its weight in gold.

Bill


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