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Film Speeds and Contrast


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#1 Jeremy Hunt

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Posted 17 November 2009 - 02:01 PM

Hi

I have a question, does higher speed films pull more contrast out of a scene?

My thinking is that if a film is more sensitive to light, then it exagerates the differences between brightnesses.

-Jeremy

Edited by Jeremy Hunt, 17 November 2009 - 02:02 PM.

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#2 David Mullen ASC

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Posted 17 November 2009 - 03:54 PM

Hi

I have a question, does higher speed films pull more contrast out of a scene?

My thinking is that if a film is more sensitive to light, then it exagerates the differences between brightnesses.

-Jeremy


In practical reality, it just depends on the design of the stocks -- the Kodak Vision, Vision-2, and now Vision-3 line have generally been designed to match as a series, with listed exceptions. So the gamma / contrast should match between stocks in that series, more or less.

Now it's probably easier to design a high-speed stock that is lower in contrast than a super slow-speed stock like 50D because you have a fast and slow layer for each color that you can play with, tweak the sensitivity. The new higher-speed Vision-3 stocks, for example, take advantage of technology designed to make the Vision-2 50D stock possible, i.e. less grainy than the EXR 50D stock before it. Kodak figured out how to make super-small, slow-speed grains for the new 50D and then used them in the slow layer of the new Vision-3 500T in order to capture another stop of extreme overexposure detail.
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#3 Dominic Case

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Posted 17 November 2009 - 08:49 PM

My thinking is that if a film is more sensitive to light, then it exagerates the differences between brightnesses.

Not really.

A faster film (more sensitive to light) simply records a different range of brightnesses.

"Sensitivity" to light is about how much (or how little) light it takes to expose the film to a certain density. "Contrast" is about how much the emulsion discriminates beween different brightnesses within a range.
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#4 Jeremy Hunt

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Posted 18 November 2009 - 12:49 PM

In practical reality, it just depends on the design of the stocks -- the Kodak Vision, Vision-2, and now Vision-3 line have generally been designed to match as a series, with listed exceptions. So the gamma / contrast should match between stocks in that series, more or less.

Now it's probably easier to design a high-speed stock that is lower in contrast than a super slow-speed stock like 50D because you have a fast and slow layer for each color that you can play with, tweak the sensitivity. The new higher-speed Vision-3 stocks, for example, take advantage of technology designed to make the Vision-2 50D stock possible, i.e. less grainy than the EXR 50D stock before it. Kodak figured out how to make super-small, slow-speed grains for the new 50D and then used them in the slow layer of the new Vision-3 500T in order to capture another stop of extreme overexposure detail.


Thanks very much David.

Where is all the info on things lik Gamma channels? i have had trouble finding info on this.

-Jeremy
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#5 Dominic Case

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Posted 18 November 2009 - 09:09 PM

Where is all the info on things lik Gamma channels?

Where did you see/hear the term "gamma channels"?

Are you asking for a definition of gamma?
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#6 Jeremy Hunt

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Posted 19 November 2009 - 08:41 AM

Where did you see/hear the term "gamma channels"?

Are you asking for a definition of gamma?


Hey, thanks for repling.

Well yes, im want to find the place/book where you learn things like gamma/alpha channels and general advanced cinematography things like film density. And all the stuff related to processing, telecine etc.

-Jeremy
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#7 David Mullen ASC

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Posted 19 November 2009 - 11:20 AM

Hey, thanks for repling.

Well yes, im want to find the place/book where you learn things like gamma/alpha channels and general advanced cinematography things like film density. And all the stuff related to processing, telecine etc.

-Jeremy


Dominic wrote a great book called "Film Technology in Post Production"
http://www.amazon.co...o...7509&sr=8-1

The Kodak website has good information on it:
http://motion.kodak....otion/index.htm
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#8 Jeremy Hunt

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Posted 19 November 2009 - 02:13 PM

Dominic wrote a great book called "Film Technology in Post Production"
http://www.amazon.co...o...7509&sr=8-1

The Kodak website has good information on it:
http://motion.kodak....otion/index.htm


Thanks very much to both of you, its great to be able to talk to professionals!!
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rebotnix Technologies

FJS International, LLC

Opal

Metropolis Post

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Glidecam

Rig Wheels Passport

CineTape

Broadcast Solutions Inc

Paralinx LLC

Visual Products

Wooden Camera

Willys Widgets

Abel Cine

Ritter Battery

The Slider

Aerial Filmworks