Jump to content

How to test spectral sensitivity of a color negative stock?


Recommended Posts

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?

Link to post
Share on other sites

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

  • Thanks 1
Link to post
Share on other sites

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.

Link to post
Share on other sites

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.

  • Like 1
Link to post
Share on other sites
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
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...