Re: SFX with IR filter

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On  1 Sep 99 at 19:15, Carlos Dias wrote:

> I'd like to know how to measure exposure values and make good pictures
> with the Ilford SFX-200 with an IR filter.
> I know it is 200 ISO but what about with an IR filter since it blocks
> visible light?

You need a relatively dark filter with Ilford SFX200 (and its Teutonic 
equivalent Agfa APX200S), darker than #25, preferably #70 or #89B, 
but not opaque.
Darker than that only decreases film speed to absurd levels, but 
has no effect on the image, neither contrast nor IR-effects.
All this unlike Kodak HIE, which already gives decent IR effects with 
#25, but where the limit is #87A.

To get an impression about what color is what code for different 
manufacturers, see my homepage for an overview of IR-filters:

http://www.a1.nl/phomepag/markerink/mainpage.htm

--                 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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