Re: (Fwd) Re: Color UV?

[Ed Scott <Dotted.Dog@xxxxxxxxxxxxxxxx>]

> BTW, which film(s) are people using ? I have read somewhere that modern
> colour films include an UV-blocking layer (this was presented as the
> reason why UV filters are not needed anymore except for protection).

Most newer Kodak color negative films do incorporate some sort of UV
filter 
so that they work better with unfiltered electronic strobe.  I think
Ektar 
films and Kodak Gold all have this UV filtering. I suspect that newer
Ektachromes 
may also incorporate UV filtering but that older transparency films do
not.  Fuji 
is probably similar but I have no information.  Sometimes you can guess
from the
spectral sensitivity curve.  If the yellow forming layer has a fairly
sharp corner 
and is rolling off rapidly at 400 nm, chances are good that some sort of
UV filtering 
is incorporated. Shooting some test frames through a Wratten 18A should
give a clue 
about any particular film.

An interesting material to try if you are into exotic materials is a
resin based
color paper used as a "paper" negative.  I think the color papers
usually have
reasonably good sensitivity into the UV region.  Load a film holder with
paper,
sized just sized as film and emulsion out.  Process as a color print or
as
a color negative.  Do not "dry normally" - instead soak the print for
several 
hours.  Then using a dowel or pencil, separate the base layer which says
Kodak
or Fuji or whatever, from the image layer.  Do this slowly, under
water.  Dry
the image layer "normally" (whatever that means in these
circumstances).  
The transparency to light can be improved by rubbing a light coating of
mineral
oil on the paper side.  This makes it messy so you do want to be carful
about
handling.  Paper negatives shot this way are unmasked but not typically
overly
contrasty and the remaining paper creates an interesting texture.  I
don't
know what purpose you had for a color material with UV sensitivity so
this
may not do anything useful for you.

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