Re: using neutral density filters with IR film.

["Sandor Mathe" <sandor.mathe@xxxxxxxx>]

From:          "Willem-Jan Markerink" <w.j.markerink@xxxxx>

> On  7 Nov 97 at 23:50, Rolland Rainbow Elliott wrote:
> 
> > I thought I read on this list a post (I think by WJ) that stated that neutral
> > density filters were transparent to infrared radiation.
> 
> Yup, and so are polaroid filters, black plastic garbage can bags and 
> non-exposed + developed sheets of E-6 slide film....:-))

I've just thought of a relatively common "neutral density filter" 
that will work with IR.  A solar filter used on telescopes for 
viewing and photographing the sun.  These are essentially metal 
plates or a metal film on glass with many small small holes. It cuts
of some large portion of the light (much more than a 16 time or 4.0 
density ND).

I'm sure they would work as a neutral density filter for IR, but are 
also unlikley to be practical (unless you are photgraphing the sun in 
IR).

Sandor Mathe  -- sandor.mathe@xxxxxxxx
(905) 670-1225 x333  --  FAX (905) 670-1344
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