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Mixing Color temps.


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#1 SSJR

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Posted 10 November 2005 - 03:12 AM

Anyone, can you please help..

First Question

So I have a shoot coming up with some Interior night shots. I will be using a 1.2k hmi for my key/moon light through a window with a tree branch as a cookie and white transparent curtains for dif. for fill im using cheated candle light and practicals . What is the best stock to intermix the two color temperatures? I'm thinking 5218 or 5279. If i do intermix two colors what's the best way to accurately meter for the two?

Second.

If im shooting a tungsten stock out doors and I put on the 85 filter. do i compensate for both light lost through the filter plus rate it at daylight iso rating or does the daylight iso rating already compensate for the light lost by the 85 filter?

Last

If I want a old home film film look for a day interior shot, what is the best 16mm film stock to use? I was thinking Kodachrome but there probably won't be not enough light even if i use the 1.2k HMI as a fake window.... My options are limited. Kodak keeps discontinuing stocks :P Maybe i can push or pull a stock. Have some kind of treatment. Any good ideas how to achieve this?
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#2 Matt Irwin

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Posted 10 November 2005 - 04:38 AM

If im shooting a tungsten stock out doors and I put on the 85 filter. do i compensate for both light lost through the filter plus rate it at daylight iso rating or does the daylight iso rating already compensate for the light lost by the 85 filter?

Just compensate for the filter. It doesn't matter if your film is daylight or tungsten balanced. You would meter the same for (example->) ASA 320 tungsten and ASA 320 daylight.

If i do intermix two colors what's the best way to accurately meter for the two?

An exposure meter will read an HMI and Tungsten source the same way: it's all light.
If you have access to a color temperature meter, you will be able to determine the color temperature of each of your sources and which gels (if any) you need in order to achieve the look you want.
If you are shooting on tungsten (3200k) balance film with no filter, a candle will render as very warm (mid-2000's k or less) and the HMI will be very blue (about 5600K, same color effect as adding full CTB to 3200k source).
Personally I'm not a fan of the un-gelled HMI "Skinemax" moonlight-- I think 1/2 CTO on an HMI (or 1/2 CTB on a tungsten source) looks better, but you should test some gels to see what you like best. Maybe use a video camera with a 3200 white balance if you can't afford to test on film?

Edited by Matt Irwin, 10 November 2005 - 04:40 AM.

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#3 SSJR

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Posted 10 November 2005 - 10:15 AM

Just compensate for the filter. It doesn't matter if your film is daylight or tungsten balanced. You would meter the same for (example->) ASA 320 tungsten and ASA 320 daylight.


Don't i loose 1/3 a stop if I do that? a 85filter only takes down 2/3. Is there a more accurate way to approach this?
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#4 David Mullen ASC

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Posted 10 November 2005 - 10:48 AM

I don't understand what you're asking. You compensate for the filter factor, that's it. It's not like using b&w film where the actual sensitivity changes by 1/3 of a stop in daylight versus tungsten.

With color film, it has a basic ASA rating that you can use (if you want to), and then you compensate for any light lost by filters. So an 85B filter loses 2/3's of a stop. So a 500 ASA film would be rated at 320 ASA when there's an 85B filter on the camera. If for some reason, you chose to put an 85B filter on a 250 ASA daylight-balanced stock, then you'd change your meter to 160 ASA to compensate for the 2/3's of a stop filter factor.

Same with using a light meter -- it doesn't matter if the light is daylight or tungsten.

I think you're confused by the fact that b&w film has two sensitivities, two ASA ratings -- one in daylight and one in tungsten, because b&w film is actually more sensitive in blue light as opposed to redder light. Color film has one ASA rating; the daylight rating on the can is just compensating for the 85B filter light loss, which is confusing.

If you use an ungelled HMI on tungsten film for moonlight and correctly underexpose the HMI light to read as "moonlight" (at full exposure it will be washed-out, too bright) you'll see that it comes out fairly blue, maybe too blue if mixed with orange-gelled lights simulating candlelight. But that's a matter of taste. Some people would put a 1/2 CTO gel on the HMI to end up with a half-blue color on tungsten film. Make sure you shoot a gray scale at the head of the scene under flat, white tungsten light.

Edited by David Mullen, 10 November 2005 - 10:51 AM.

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#5 SSJR

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Posted 10 November 2005 - 04:36 PM

If you use an ungelled HMI on tungsten film for moonlight and correctly underexpose the HMI light to read as "moonlight" (at full exposure it will be washed-out, too bright) you'll see that it comes out fairly blue, maybe too blue if mixed with orange-gelled lights simulating candlelight. But that's a matter of taste. Some people would put a 1/2 CTO gel on the HMI to end up with a half-blue color on tungsten film. Make sure you shoot a gray scale at the head of the scene under flat, white tungsten light.



Are there any cheap color meters out there ? can I use my DSLR?, so that i can monitor whats going on when i am mixing these color tempretures? Also if i want a after time interior to look like sunset/ magic hour... what is the best way to gel my 2 key HMI comming from two diffrent windows?

Edited by SSJR, 10 November 2005 - 04:45 PM.

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#6 Matt Irwin

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Posted 10 November 2005 - 09:58 PM

Are there any cheap color meters out there ?


There are cheap ones out there, but it's unlikely you'll find a 3 color meter (used) for less than US $200. I saw a Gossen Sixticolor analog meter on eBay for $60, but it only reads blue<->orange, and not green<->magenta. The choice meters are the minolta digitals, but they will run close to $1000 for the latest model.

You probably could use a DSLR, but I wouldn't judge color from a still on anything but a calibrated monitor (at least for these purposes).

Edited by Matt Irwin, 10 November 2005 - 10:01 PM.

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#7 David Mullen ASC

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Posted 11 November 2005 - 12:41 AM

Most people don't use color temp meters to do creative things like how blue to make moonlight or how warm to make sunset -- a meter can't really tell you how blue something will LOOK on film anyway.

I mean, you already know that an ungelled HMI on tungsten-balanced film is around 5600K or so, but obviously you aren't sure how blue that will look, so a color temp meter isn't going to help in that regard. It would just tell you that the HMI was 5600K.

Color temp meters are more for things like figuring out how much green is in a particular fluorescent, how well a set of HMI's match each other, etc. A color temp meter is more of a technical tool and more than likely, your gaffer will be the one using it more than you need to. I've never needed to own a color temp meter even after shooting 30 features, although I occasionally ask the gaffer to pull his meter out to check something (like "if I dim that 2K down by 50%, what color temp am I getting so I can gel another light to match it?")

In terms of how much orange gel is needed to create a sunset effect, well, that comes down to using your eyes, and to experience -- and testing. Just like how blue should moonlight be, or even if you want to add a little green to it, etc.

One of the basic things I do when testing a stock is shoot a face in white light, then gel the light with Full Orange and then Full Blue to see how saturated those two colors get. So then I have an idea, for example, of how orange a face will look when lit with a light gelled Full Orange; from that, I may decide to just use Half Orange or whatever. You need to know the likely extremes of choice, just like you should know what a shot two stops overexposed and two stops underexposed looks like.

Obviously if you are using 3200K tungsten-balanced film, you'll need Full CTO (Full Orange) or Full CTS (Full Straw) just to correct a daylight HMI to 3200K and end up with a "white" light, so if you want an orange sunset effect, you need to add even more orange or straw to the HMI (or whatever colors you think of as sunset.) This is just a matter of taste and what the scene needs, since some sunsets can be mildly golden orange while others can be deep orange-red.

Edited by David Mullen, 11 November 2005 - 12:44 AM.

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