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16mm lighting question


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#1 Elliot Rudmann

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Posted 17 May 2006 - 08:41 PM

In about three weeks I will be shooting a short film on a bolex with Kodak's 7205 stock. Certain indoor scenes call for a warm look, and I was thinking about using uncorrected tungsten lights in some interior scenes, but I'm afraid that doing so will result in too much of an orange-ish look. Would gelling the lights 1/4 CTB be helpful or should I just go ahead and let the tungsten be tungsten? If anyone has any screenshots of the 7205 stock I would appreciate it.

My last question concerns my confusion with overexposing the negative and then "printing down." If I'm correct, would I shoot the color chips rating 7205 at 125 ISO (overexposing 1 stop) and then does the lab (using the chips) compensate for the overexposure by printing the negative down while developing? Is this the same as pull processing? Or is it something done in telecine? I know this has probably been asked a lot, so I apologize and, as always, appreciate your knowledge and feedback. Thanks!

elliot
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#2 David Mullen ASC

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Posted 17 May 2006 - 10:51 PM

Printing and/or telecine transfer and developing are separate stages. The film has to be developed before it can be printed or transferred. The lab doesn't know what's on your film or how you exposed it until AFTER it has been processed -- they just want you to tell them to process it normally, or pull or push-process it, and by how many stops.

You have to understand that there are many variations possible -- it all depends on the look you want, and how dense you want the negative to be.

Overexposing a negative and processing normal will result in a denser-than-normal negative. Remember that an overexposed image on a negative is darker, denser overall, and of course the darkest areas correspond to the brightest areas of the real (positive) image.

Overexposing a negative and pull-processing by the same amount (let's say, overexposing by one stop and then pull-processing by one stop) will result in a negative with normal density.

Underexposing and processing normal will result in a thinner-than-normal negative (less dense).

Underexposing and push-processing by the same amount will result in a negative of normal density.

All these approaches produce different results in terms of graininess, contrast, black level, color saturation, etc. and will affect how you print or transfer the image.

Typically, you want the benefits of a slightly overexposed negative that is developed normally so that the negative ends up slightly denser-than-normal. So you rate a 250 ASA stock at 160 ASA, let's say, and process normal. So now your processed negative has a 2/3-stop overexposure; the timer printing the negative can then print that image at higher-than-normal printer light numbers (printing "down") to reduce the brightness of the image down to normal. The colorist transferring the negative will just darken the image to look normal in brightness. It helps if you shot a grey scale at the head of the roll at the same level of overexposure so that by adjusting the image of the grey scale to look "normal" by bringing the brightness down, the following footage on the roll would also have been brought down to normal as well.

Now you could overexpose the negative by one stop and then pull-process by one stop to end up with a negative of normal density. You get the benefits of less graininess, but also you tend to get a lower-contrast image with softer colors, and the blacks are normal. If you had overexposed by one stop and processed normally, then printed the image down to compensate, you'd also get less graininess, but you'd have deeper blacks in the print, which tends to make the colors look more saturated. The contrast may even look higher because of the deeper blacks, a snappier image. I'm talking about printing here; there are fewer benefits to an overexposed negative for a telecine transfer, although you still get less grain and better shadow information -- but the black levels are more a function of the electronic color-correction, and on some telecines, if the negative is too dense, you start to get noise in your highlights because the negative is so dark (dense) in those areas.

Too much overexposure and the opposite starts to happen in the print -- instead of a snappier image, because now you've put too much picture information on the shoulder of the characteristic curve, the gamma starts to flatten out, the contrast gets lower, and you lose highlight details. You also may hit the top of the 50-point printer light scale, making it harder to balance the colors.
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#3 David Mullen ASC

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Posted 17 May 2006 - 11:02 PM

In terms of using tungsten lights on daylight stock, uncorrected tungsten would look as orange as Full CTO on a tungsten light on tungsten stock, which is fairly strong, the color of a deep orange sunset or firelight. Now it may look less orangey if it was bright, overexposed light, like hot sunlight, but it still would be pretty warm. But I have used uncorrected tungsten lights on daylight stock to simulate a sunset look.
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#4 Michael Nash

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Posted 17 May 2006 - 11:04 PM

Are you making a print from your negative, or transferring the neg to video? You seem to be confused about the workflow.

"Printing down" refers to changing the printer lights to make a darker print image from the negative. This step is separate from the development of the negative.

Push- or pull-processing refers to over- or under-developing the negative to restore a normal density (effectively the "brightness") to the negative.

I think what you're thinking of is overexposing the negative for extra density and processing normally, then "printing down" to yield a normal-looking brightness on the print.

The TELECINE process has nothing to do with printing; it strictly refers to the transfer of the image to video. You can still overexpose the neg and process normally for extra density, and then set up the transfer for a normal-looking brightness.

In either case (print or telecine) you would shoot an 18% gray card overexposed by the desired amount, and that image becomes the brightness reference for the lab color-timer or telecine operator.

For your iinteriors you'll have to decide how warm you want "warm" to look. I would start with 3/4 CTB on your tungsten lights if you can afford that much light loss. You could even shoot your tungsten light "clean" if you wanted and then adjust the color at either the printing or telecine step. Just be sure to shoot your gray card under the color of light that you want to appear "white."
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#5 Elliot Rudmann

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Posted 18 May 2006 - 12:29 AM

Mr. Mullen and Mr. Nash - I cannot thank you enough for your detailed and clear responses. My primary experience with 16mm has been in shooting color and b&w REVERSAL, not negative film, so I was blurring the distinction between processing (developing the negative) and then actually printing that negative to a positive....oh how I'm going to miss the simplicity and cost of shooting reversal. As for the lighting question, I'm going to test the look with different CTB gels with my 35mm SLR - hopefully that will give me an idea of what it will turn out like. Thanks again!
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