Seth Baldwin Posted May 19, 2021 Posted May 19, 2021 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?
Sergey Surin Posted May 21, 2021 Posted May 21, 2021 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 1
Seth Baldwin Posted May 21, 2021 Author Posted May 21, 2021 I've already done a clip test to establish dynamic range. But I want to find a way to test the individual sensitivity of each dye to particular wavelengths of light.
Premium Member David Mullen ASC Posted May 21, 2021 Premium Member Posted May 21, 2021 Wouldn’t you also need a light meter that was accurate for specific wavelengths?
Premium Member Phil Rhodes Posted May 21, 2021 Premium Member Posted May 21, 2021 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. 1
Seth Baldwin Posted May 21, 2021 Author Posted May 21, 2021 (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 May 21, 2021 by Seth Baldwin
Sergey Surin Posted May 23, 2021 Posted May 23, 2021 If you meant individual sensivity of each part of the spectrum (Red/green/blue) a have them too
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