Re: IR effect from Ilford SFX200

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

On 16 Mar 97 at 21:30, George Ling wrote:

> I have been experimenting with this Ilford SFX200 with #25 red filter,
> wanting to *capture* some IR effect like darkened sky, white vegetation,
> etc. 
> 
> I can only achieve the former but not the latter. A direct sun-lit green
> lawn does not give me a whitish look, as it would with Konica 750 & #25
> red filter for example.
> 
> Is this the way Life is with SFX200?  Or do I need to use a different
> filter to get the IR effect from vegetation?

You need to go close to the spectral limit of SFX to capture the Wood 
effect. The Wood effect starts at 695nm, and SFX peaks at 720nm, with 
a limit at 740nm. A #89B would be the filter of choice here, to block 
most of the lower range.
Check my homepage to get a 'feel' in spectral differences of these 
filters:
http://www.a1.nl/phomepag/markerink/mainpage.htm

--
Bye,

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      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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