Re: DAYLIGHT, LOADABLE, Kodak, B&W, Infrared, Film, for, sale, $8.45/roll

[Otto Giesenfeld <otto.giesenfeld@xxxxxxxxxxxx>]

--On den 12 juni 2000, 13:39 -0400 ADavidhazy <ANDPPH@xxxxxxxxxxxxxxxxxx>
wrote:

>> 2.  Just because you exposed and developed B&W film so that it has an
>> opaque emulsion COATING to IR light DOES NOT mean that the film base will
>> NOT pipe light through to the inside of the casette. <snip>
> 
> Agreed. But this I had checked out and there was no "piping" taking place.
> I had used Tech Pan and T-Max 100 processed to D-max as leaders.
> 

For a developed B&W emulsion not to stop light from piping through the
film, the indices of refraction would have to be quite different between
the base and the emulsion. While this is not impossible, it does at least
seem unlikely that they would differ enough to prevent film-base light from
leaking into the emulsion. After all, you might then get light-piping even
with visible light and panchromatic film, as the antihalation layer is not
part of the actual base. Anyway, the above assumptions seem to be in
agreement with Mr. Davidhazy's observations.

Otto Giesenfeld
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