Re: Infrared Film Spectral Response

[Otto Giesenfeld <otto.giesenfeld@xxxxxxxxxxxx>]

--On den 29 september 1999, 13:32 -0400 George L Smyth
<glsmyth@xxxxxxxxxxxxxxxxx> wrote:

> On Wed, 29 Sep 1999 gmm25@xxxxxxxxxxxx wrote:
> 
>>     Hello, I am new to this list, and was wondering if anyone had any
>>     comments on finding, or making a film that was sensitive to further
>> infrared light. For instance the kodak high speed infrared is sensitive
>> out to about 1000nm, Does anyone have any ideas on obtaining or
>> sensitizing a film so that it can "see" light perhaps out to 1500nm?
>> 
> It is not possible to sensitize film beyond 1200nm.  There is a Russian
> film (I am told) that does extend to this point.  However, it needs to be
> constantly refrigerated - i.e. it would be fogged by the time it gets to
> you.
> 

Perhaps the most reasonable way to go for photography up to 1500nm is
digital. The Sony video cameras that were sold for a while with the ability
to see through certain clothes had more IR sensitivity than film, one may
assume. Les Jorgensen lately wrote to the list: "I've been using the Phase
One digital camera with a 87c Kodak gel. I have to take off the special
dichroic blue filter (which blocks out the offending red +spectrum for
normal color intergrity) and find nearly normal shutter speeds."

If photos with the 87c filter can be taken at almost normal shutter speeds,
it would suggest that the sensitivty may continue rather far below the 87c
cutoff frequency.

Otto Giesenfeld
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