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How to test spectral sensitivity of a color negative stock?

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I'm trying to test the spectral sensitivity of an expired Kodak motion picture stock. How would i achieve this? Would i expose the film to isolated wavelengths at a single exposure value to see how each dye in the film responds after development?

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We have such kind of service  Here in Moscow (laboratory of Mosfilm company) , I used it two weeks ago, they took 10 meters from each roll (in completely dark conditions) i gave them and then they made full check wth all information about how it holds in terms of sensitivity/dynamic range / fog level (hope I translate it right) 

And it seems that it could be done in every film developing laboratory all around the world so you just need to ask about it

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For this you'd need a monochromator, which fires a beam of light through a diffraction grating to split it up into the spectrum, then passes the resulting light through a slot to select just one colour. The slot may be variable width. Given a sufficiently broadband light source (incandescent bulbs are widely used) light of any wavelength and bandwidth can be created. Monochromators are usually metered using a photomultiplier-based detector.

Quite whether it would be reasonable to apply all of this to testing suspect film stock is another matter.

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Posted (edited)
3 hours ago, David Mullen ASC said:

Wouldn’t you also need a light meter that was accurate for specific wavelengths?

Yeah, I'd likely need a spectrometer from Sekonic, can rent one thats fine. Or what phil said sounds promising. 

Edited by Seth Baldwin
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