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light meter + video


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#1 Dalton Swift

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Posted 26 February 2008 - 05:43 PM

Im wondering if someone can explain if/how a meter is helpful shooting on video.

for video how should the ASA be set ?


thanks.
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#2 Michael Nash

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Posted 26 February 2008 - 05:45 PM

Try a search; this has been discussed many times.
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#3 Dalton Swift

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Posted 26 February 2008 - 07:01 PM

I'm sorry, I did a search and nothing turned up
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#4 Jess Haas

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Posted 26 February 2008 - 07:37 PM

You don't want to use a meter to set your cameras exposure, but it can be very helpful while lighting. Most video cameras seem to be in the 320-500 range so I usually set my meter somewhere in there to get an idea of what light levels will be necessary.

~Jess
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#5 Buddy Greenfield

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Posted 26 February 2008 - 09:24 PM

I?m not sure this will help you much, but I found it interesting at the time:

About a year ago I read an article which dealt with the many shortcomings of plain old consumer grade video, in it it was suggested that one of the reasons the world is filled with bad home video, is that the lighting it needs (125FC - 180FC) would never really be suggested by camcorder manufactures because A: It would make their product sound inferior and B: The potential for lawsuits by suggesting use of hot/ potentially dangerous lights doesn?t make for sound business in today?s lawsuit happy world.

I don?t know how true all of that is, but I figured I would experiment, so I tried the world?s biggest POS JVC Hi 8 camcorder with about 125 FC of bounced (Off white wall/ceiling) 650W Bell and Howell movie flood light, the results were dramatically favorable, like night and day in fact.
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#6 Brian Dzyak

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Posted 26 February 2008 - 10:09 PM

There is a way to determine the effective ASA of your specific video camera, but I won't go into that here.

I don't generally use a meter when lighting, except when I shoot greenscreen, as I did earlier today. I use an old Spectra to make sure my light is even across the green. I measured my Kinoflo output and had the footcandle reading. From that, I was able to set my backlight and key without ever looking through the lens. I had a "new" camera (F900)which I didn't know the ASA of, but it didn't matter. I wound up shooting at about a T4 which was more than ok.
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#7 Michael Nash

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Posted 26 February 2008 - 10:32 PM

http://www.cinematog...ite=light meter
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#8 David Michael Conley

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Posted 16 May 2008 - 11:20 PM

http://www.cinematog...ite=light meter


Is this link broken or does the topic still exist? I am shooting a green screen with an F900 tomorrow. I have lit some green screen, but this is a bigger show and I just wanted double check that what I was thinking was correct. I should be lighting the GS one stop under for video? I spoke to a post special FX guy who gave me that info. Is that correct? I always thought it was one stop over, but maybe that is just for film. Maybe I am wrong all around. If anyone is on the boards now, I would love some advice. Thanks!
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#9 Michael Nash

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Posted 17 May 2008 - 01:28 AM

Is this link broken or does the topic still exist? I am shooting a green screen with an F900 tomorrow. I have lit some green screen, but this is a bigger show and I just wanted double check that what I was thinking was correct. I should be lighting the GS one stop under for video? I spoke to a post special FX guy who gave me that info. Is that correct? I always thought it was one stop over, but maybe that is just for film. Maybe I am wrong all around. If anyone is on the boards now, I would love some advice. Thanks!


You don't want to to overexpose your greenscreen! One stop under should be okay; at key is often better for video. What matters most is the saturation of the green not the luminance, and you get the best color saturation/least noise between about 40-55 IRE.
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#10 David Michael Conley

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Posted 17 May 2008 - 06:43 AM

You don't want to to overexpose your greenscreen! One stop under should be okay; at key is often better for video. What matters most is the saturation of the green not the luminance, and you get the best color saturation/least noise between about 40-55 IRE.


That makes sense that the saturation would be the main focus. I will try exposing it right on and see where I am. I am not sure where I had heard about overexposing by one stop. Thanks Michael!
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#11 Walter Graff

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Posted 17 May 2008 - 02:55 PM

For VIDEO, any story of over exposing chromakey screens is a myth. A MYTH!!! Chromakey is about saturation when it comes to the screen alone as exposed to the camera but done in a ratio that makes the blue or green as pure to its vector target as possible. As for overexposing, the question is to what. If you are saying over expose it to your talent for video then you need ot understand one thing. Your screen in terms of lighting has absolutely nothing to do with your foreground except when to use blue or green which you do depending on contrast of the foreground to the screen (eg a white guy in only a bathing suit would key better over blue). In that case contrast becomes important because chromakeyers today not only use color as a separator but contrast so white skin is farther away from blue than green and dark skin farther away from green than blue. Other than that you expose green and expose blue to both the correct saturation and luminance as seen on a waveform/vectorescope. Green likes to be as close to 50-55 units of luminance as possible and blue likes to be around 40-45 units. If you follow those guidelines, then the five thousand myths about green screen that exist on the web will all go away.
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#12 e gustavo petersen

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Posted 17 May 2008 - 09:59 PM

As to your first question... For what it's worth, here's an example of how I used a light meter when shooting a recent feature on HD.

Several night scenes required high shutter speeds. I might tell the Chief Lighting Tech that we needed 70 foot-candles because we're shooting at 1/250 shutter (equiv. 34.5°). He and the crew could work from that until the camera could be placed and we could see what it was like on the monitor/scope and then "season to taste". This worked out great because he didn't need to know how I was rating my camera, what filter compensation I was using, etc. I, of course, needed to keep track of all those considerations and adjust with him accordingly.

It goes hand-in-hand with the comments about pre-lighting. And if your crew isn't highly experienced, using a meter goes a long way to getting the lighting close. It's also very helpful when taking notes about the lighting should you need to return to that set or even if you just want notes about how a set was lit for future reference.

As to your second question... Michael's right there are numberous discussions about determining your ASA/EI on this and other boards. As we've all heard time and time again, test, test, test.
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