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latitude of 7231 and 7222


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#1 kief sloate-dowden

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Posted 20 March 2006 - 12:40 PM

Hello!

I'm a student shooting my first film with negative stock. I was wondering if anyone can tell me the latitude of plus-x 7231 and double-x 7222. The interiors (7222) will be dark and the exteriors (7231) will be quite bright, due to snow on the ground. If anyone knows the limits of under and over exposure of the two stocks, that would be great. I can't find anywhere that Kodak gives this information. Thanks.

-Kief
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#2 Dirk DeJonghe

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Posted 20 March 2006 - 01:53 PM

You may want to have a look at my website under 'downloads'. There is a method many of my customers use to determine the real speed of film stock taking into account the processing, lens, exposure meter and all other variables.

Basically you try to find the point where a -4 stops grey chart just begins to register. That means you have 3.5 stops underexposure latitude. You determine the overexposure latitude in a keylight test after having run the first test. It's a two step process but very precise.

Thanks to Ansel Adams. 'Place the shadows and let the highlights fall in place'.
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#3 John Pytlak RIP

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Posted 20 March 2006 - 04:24 PM

Hello!

I'm a student shooting my first film with negative stock. I was wondering if anyone can tell me the latitude of plus-x 7231 and double-x 7222. The interiors (7222) will be dark and the exteriors (7231) will be quite bright, due to snow on the ground. If anyone knows the limits of under and over exposure of the two stocks, that would be great. I can't find anywhere that Kodak gives this information. Thanks.

-Kief


The published Kodak data for each film on the Kodak website includes the sensitometry of the film:

http://www.kodak.com...4.4.8.4.4&lc=en

Posted Image

http://www.kodak.com...4.4.8.6.4&lc=en

Posted Image

As you can see, the contrast (gamma) and latitude of each film is very dependent on the processing conditions. Labs can adjust the time of development to optimize the tone reproduction, so you should work with your lab to choose and test the optimum conditions of exposure and processing.
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#4 Michael Morlan

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Posted 27 May 2006 - 10:52 PM

It would be nice to receive a simple answer. :) How many stops on the straight-line portion?

Would somone check me on the following assertion?

I did a bit of rough reverse-engineering for the 7231 characteristic curve when I found that Kodak '29 documentation includes f-stops and log-exposure in its characteristic curve graph. I guessed 1.0 Log Exp = ~ 3.2 f-stops. (Should it be 3.0?)

By reviewing the characteristic curve and doing some quick math, 7231 has a straight-line latitude of around 6 stops. Testing, as described above, can reveal how much the exposure breaks down as you push latitude into the knee and the toe as well as where your middle-point is.
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#5 Bryan Darling

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Posted 27 May 2006 - 11:52 PM

I've directed two films shot entirely with 7231 & 7222. 7231 is tempremental in that it is very contrasty. You need to really watch the times of day and lighting situations. 7231 is great in controlled environments such as using silks and bounce outdoors. 7222 has less contrast and can work in about any environment. We did full outdoor and indoor in all sorts of situations. I would get at least one or two 100' rolls of each and shoot them in different environments and you can see what you prefer.
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#6 John Pytlak RIP

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Posted 30 May 2006 - 03:49 PM

I've directed two films shot entirely with 7231 & 7222. 7231 is tempremental in that it is very contrasty. You need to really watch the times of day and lighting situations. 7231 is great in controlled environments such as using silks and bounce outdoors. 7222 has less contrast and can work in about any environment. We did full outdoor and indoor in all sorts of situations. I would get at least one or two 100' rolls of each and shoot them in different environments and you can see what you prefer.


As the sensitometric curves I posted show, for B&W negative films, you can easily adjust contrast by changing the developer time or temperature.
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Visual Products

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Paralinx LLC

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Rig Wheels Passport

Glidecam

Technodolly

The Slider

Metropolis Post

FJS International, LLC

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New Pro Video - New and Used Equipment

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