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please sooth my confused mind


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#1 Ollie Bartlett

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Posted 13 July 2007 - 09:25 AM

hi all,

ok, heres my conundrum. ive been asked to shoot an interior night scene and replicate the light so as to look like moonlight coming through the window. i only have tungsten lights to use and am trying to find a solution. i may have figured something out by scanning these forums but i would really appreciate it if somebody could tell me if im heading in the right direction.

tungsten runs at 3200k and so i can replicate 5500k by using a full CTB gel.

then...

i add some 1/2CTB and 1/4 plus green (ontop of the full CTB) which will give me a decent moonlight tone.

as i said, i have no idea if this works but its what i can figure out from this, the most hallowed of forums.

any advice would be very much appreciated.

cheers guys,

ollie
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#2 David Mullen ASC

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Posted 13 July 2007 - 09:39 AM

On 3200K film stock, or 3200K white balance, then Full CTB is already quite blue-looking on a tungsten lamp if underexposed for a moonlight effect. Many people just use 1/2 CTB for a pale blue effect.

You don't need to correct to 5500K first and then add more blue unless you are using daylight-balanced film stock.
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#3 Ollie Bartlett

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Posted 13 July 2007 - 10:04 AM

ok lets me get this straight,

because id be using a 3200k white balance, a full or half ctb would give me the desired effect from a tungsten if stopped properly. id only need to add the extra ctb if i was shooting with a 5600k balance so that the colour temperature of the lights matched the balance (im not sure that this sentence even makes sense).

just out of interest, why has the person on the thread i pinched the info from recommended an additional 1/4 plus green to the mix? what effect does this additional tone give to the light when blended with the CTB?

ollie

ps im setting up the lights, gels and cam in my living room right this second as a test so ill let you know how it goes. cheers david

Edited by ollie bartlett, 13 July 2007 - 10:09 AM.

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#4 John Holland

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Posted 13 July 2007 - 11:34 AM

I would just use the 1/2 ctb and the 1/4 green , moonlight is not blue its almost monochrome ,so the green combination will help give you that look . good luck.
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#5 Jonathan Bowerbank

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Posted 13 July 2007 - 12:19 PM

just out of interest, why has the person on the thread i pinched the info from recommended an additional 1/4 plus green to the mix? what effect does this additional tone give to the light when blended with the CTB?


Some people like to have a hint of green in their moonlight, it's just a matter of taste & preference.

I like to use just a 1/2 CTB underexposed so it's just a little bluish. Full CTB is a bit much for my taste. I like to have a lot of white in my moonlight.
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#6 Chris Keth

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Posted 13 July 2007 - 12:40 PM

ok lets me get this straight,

because id be using a 3200k white balance, a full or half ctb would give me the desired effect from a tungsten if stopped properly. id only need to add the extra ctb if i was shooting with a 5600k balance so that the colour temperature of the lights matched the balance (im not sure that this sentence even makes sense).


Think of it in two steps. Step one is to correct the light to be "white" on your particular film. Step two is to add the color.

In this case tungsten film needs tungsten lights for white to there is no correction in step 1. Step two is just to add half-CTB (with a bit of green if you want) for the color.

To get the same effect with daylight film and the same lights: Step 1: Full CTB to correct the tungsten lights to daylight. Step 2: add half-CTB on top of the full to get the blue color.

Note that these are just examples that ignore the light loss of CTB. You would need very big lights to hold up to one-and-a-half strength CTB and still put out significant light.
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#7 John R Hudson

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Posted 16 July 2007 - 06:58 AM

Depending on the size of your tungsten lights and the worry of losing a stop, one may consider correcting the color temp in post.

Edited by John R Hudson, 16 July 2007 - 06:59 AM.

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#8 Stuart Brereton

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Posted 20 July 2007 - 11:41 AM

Depending on the size of your tungsten lights and the worry of losing a stop, one may consider correcting the color temp in post.


Another alternative (if you're shooting tape) is to white balance for about 2700 kelvin. This will send your tungsten lamps slightly cold & blue.

To do this, simply place a piece of 1/4 or 1/2 CTO over the lens whilst white balancing.
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#9 JD Hartman

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Posted 20 July 2007 - 01:09 PM

Other options for gels are: Bastard Amber or 1/2 CTO or 1/2 Straw. Since you are testing this out prior to shooting (an excellent idea), you can see which "look" you prefer for moonlight.
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