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Long Exposures


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#1 Rachel Oliver

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Posted 16 February 2006 - 06:40 AM

Hi;

I need to shoot some long exposure time-lapse of a river. It's in daylight full sun and I'd like to hold the shutter open for 10 seconds in order to gain extreme motion blur of the river. I will most likely be using 50D neg (7245/7201) and lets say an F-Stop of 11... Can anyone give me any pointers as to how to work out the correct ND compensation (taking repriocity faliure into account) for a 10 second exposure? At a guess I'm thinking a 1.5...

Olly
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#2 Stephen Williams

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Posted 16 February 2006 - 07:50 AM

Hi;

I need to shoot some long exposure time-lapse of a river. It's in daylight full sun and I'd like to hold the shutter open for 10 seconds in order to gain extreme motion blur of the river. I will most likely be using 50D neg (7245/7201) and lets say an F-Stop of 11... Can anyone give me any pointers as to how to work out the correct ND compensation (taking repriocity faliure into account) for a 10 second exposure? At a guess I'm thinking a 1.5...

Olly


Hi,

I would shoot 12 seconds at T8 with 10 stops ND3 ( take care your rental house may give you a 0.3, 1 stop). I have allowed 1 stop for recipriocity failure and allowing for slight overexposure. Depending on where the sun is you may want increase exposure slightly, but thats a good starting point.

In normal sunny conditions with 50asa, 48 fps is f11, 24 fps is f16, 12fps is f22, 6fps is f32, 3fps is f44, 1.5fps is f64, 0.75fps is f88, 1.5 spf is f128, 3spf is f176, 6spf is f256, 12 spf is f352.

Stephen
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#3 Rachel Oliver

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Posted 16 February 2006 - 01:41 PM

Hi;

Great advice, Thanks Stephen.

Olly
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#4 John Pytlak RIP

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Posted 17 February 2006 - 02:01 PM

Hi;

I need to shoot some long exposure time-lapse of a river. It's in daylight full sun and I'd like to hold the shutter open for 10 seconds in order to gain extreme motion blur of the river. I will most likely be using 50D neg (7245/7201) and lets say an F-Stop of 11... Can anyone give me any pointers as to how to work out the correct ND compensation (taking repriocity faliure into account) for a 10 second exposure? At a guess I'm thinking a 1.5...

Olly


The Kodak website lists technical data for each film that usually has reciprocity information:

http://www.kodak.com...0.1.4.4.4&lc=en

http://www.kodak.com...4.4.4.4.4&lc=en

http://www.kodak.com...&lc=en#recichar

Reciprocity Characteristics (for 5201)
You do not need to make any filter corrections or exposure adjustments for exposure times from 1/1000 to 1 second. For exposures in the 10 second range, it is recommended that you increase exposure by 1/3 of a stop and use a KODAK Color Compensating Filter CC 10R.


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#5 Rachel Oliver

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Posted 17 February 2006 - 02:57 PM

The Kodak website lists technical data for each film that usually has reciprocity information:

http://www.kodak.com...0.1.4.4.4&lc=en

http://www.kodak.com...4.4.4.4.4&lc=en

http://www.kodak.com...&lc=en#recichar


Hi;

Thanks John, What could I expect to see without the compensating filter? As this is for telecine so perhaps I could deal with colour shifts there.

Olly
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#6 John Pytlak RIP

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Posted 17 February 2006 - 04:10 PM

Hi;

Thanks John, What could I expect to see without the compensating filter? As this is for telecine so perhaps I could deal with colour shifts there.

Olly


Because of the great latitude of the film, a 10CC Red is a negligible correction, and can easily be color graded.
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