Archived posting to the Leica Users Group, 1998/11/26

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Subject: Re: [Leica] Tungsten film?- in re filter correction.
From: "Dan Post" <>
Date: Fri, 27 Nov 1998 00:38:33 -0500

If you scan- and the correction is electronic (easy and immediate- instead
of waiting 5 minutes for the prints to clear the processor) if you over
exposed the film, you would certainly over expose the magenta and cyan
sensitive layers, but you should get more information in the blue layer...
The principle here is if the blue sensitive layer is NOT exposed, you can't
add information to it by filtering later. IT is either there or not- BUT if
the magenta and cyan is overexposed, it's easier to take out the excess
information, balancing to the blue sensitive layer.
I would say that you try the new superia films- they have a fourth layer
like Reala and NPS and I have really been taken with the Superia 400. It
should help in mixed light situations.
Try overexposing a bit and then correct the scans and see if the bluish hazy
cast and graininess diminish.
It is of interest to note that fluorescent light is much easier to correct;
it seems that the layers don't have a sharp cutoff response and the lack of
red light in fluorescent is partly made up for by the red sensitive layer's
partial sensitivity to the yellow spectrum of the light. Tungsten can be a
real bear, especially since a lot of folks are using the commercial service
bulbs rated at 130 volts. They last longer at 120 volts, but are really
yellow. We got some here  at home because they last so long, and when I
tried to shoot to test a Summarit, I was surprised myself at how yellow the
light was- almost red.
Well so long for now!