Ira Tiffen recently wrote (in a CML archive file) :
>>The LL-D (Low-Light Daylight)filter, as developed in the late '80's by Ed Ortman (formerly Kodak's chief test cinematographer), and myself, was based on Ed's observation that much of the effect of a conversion filter to accommodate tungsten film to daylight was due to the absorption of UV. The rest of the LL-D spectral curve serves as a means to further tweak the color rendition while minimizing the amount of light absorbed. This is why the LL-D allows, after color timing, the virtually identical color rendition as if you had used an 85B, but without requiring any exposure compensation.<<
How much exposure compensation does the LL-D require without taking color timing into account? In other words, to produce a negative of equal density and color balance to an 85B . (Or does the LL-D depend on some degree of color timing to fulfil its purpose?)
Marin County, CA
The LL-D doesn't really need an exposure compensation, but it is not a full correction, more of a partial correction combined with UV filtration. You still need to make some timing corrections in post (also because one often pulls the 85B filter in low-light situations where there is more blueness to the daylight than when shooting in sunlight, like in deep shade or at twilight.) I think the filter was particularly useful back in the days of 5247, which was more sensitive to UV haze when the 85B filter was pulled.
I've sometimes used the LL-D when shooting on tungsten stocks under Cool White fluorescents because it seems to help cut down a little of the blue cast without losing exposure like a fluorescent correction filter, but I never tested this thoroughly to know for sure how much it was helping in terms of the printer light adjustment.
Cinematographer / L.A.
Dan Drasin wrote :
>How much exposure compensation does the LL-D require without >taking color timing into account?
David Mullen gave a good account of how the LL-D, while requiring no exposure compensation, still needs color timing to do its work. The reason for the LL-D is that originally unfiltered film will not be able to render all colors the same as if you had used an 85B (when the situation would call for one) with color timing alone. Ed Ortman had noted that when lower light levels wouldn't allow for the 2/3 stop light loss of an 85B, and when shooting unfiltered to accommodate, the result would be noticeably different when timed for proper flesh tones- mainly in that neutrals and whites would be warmer, more yellow.
According to Kodak's lab tests at the time (late '80's), the LL-D allows the virtually identical color rendition (after color timing) as if you had used an 85B.
Referring to Dan's question, increasing exposure would not be expected to alter the requirement for color timing.
The Tiffen Company
Hauppauge, NY 11788
Just a quick comment…
Whilst these filters DO work with film don't for a second think they'll work with video/HD.