Re: [APML] Preflash film with colored light?

[George Anderson <georgea@cam.org>]

Hi Gil

The films spectral responses are normally graphed in the tech pub for
the film. Both Kodak and Fuji post online the tech pubs for their films.
To get an idea as to which films may fit the scenario have a look at
Robert Reeves film tests and Don Westergrens site as well. Don's site is
more up to date (IIRC) and see if their is a film that fails on the red
due to reciprocity. Then check the tech pub top be sure that the red
response extends above 660nm. If so it is a possible candidate.

George

Clear skies and good health

Gil McFarlane wrote:
> 
> I want to test this out too, how do I find out if the
> film is sensitive to 700nm or so?  Is it in Kodak and
> Fuji's technical papers?
> 
> - Gil
> 
> --- George Anderson <georgea@cam.org> wrote:
> 
> > Hi Gil
> >
> > It is one of the things on my to do list if we ever
> > get any clear skies
> > without a moon. I have two B&W films to finish
> > testing and then I want
> > to have a shot at one of the colour films that has a
> > weak red response
> > due to reciprocity failure.
> > The film has to extend beyond 650nm to start with
> > otherwise it is a lost
> > cause. If there is no sensitivity at that wavelength
> > then preflashing
> > won't do a thing for the film as far as catching
> > H-Alpha light.
> > The idea is to bump the red "fog" level up to where
> > the exposure is more
> > colour balanced and hopefully keep more of the red
> > photons which strike
> > the film rather than have them bleed off due to an
> > insufficient number
> > striking the film grains.
> > BUT, the whole idea is theoretical and may bear no
> > fruit other than to
> > create other problems with the negative.
> > At the current rate of shooting days I may get a
> > chance to try this out
> > in November.
> >
> > George Anderson
> > Montreal Canada
> >
> > Clear skies and good health
> >
> > Gil McFarlane wrote:
> > >
> > > Has anyone experimented with preflashing color
> > > negative film with red light to see if it improves
> > the
> > > film's red responsivity?
> > >
> > > - Gil
> > >
> > >
> 
> 
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