Re: FS Wratten #87 (IR) & #25 (red) Gelatin Filters

["Jason Revell (in5)" <jason.revell@xxxxxxxxx>]

I have shot HIE in overcast conditions and had reasonable results.  I
must
confess never to have used it during rain but when the sky is fully
overcast
there is still the same IR 'effect' to be made from the scenes.  I find
I can
even use the same film speed rating wether it is strong sunlight of a
dull
overcast day (all metered through the a dark red filter).

The problem lies in the fact that if you include any sky in the
photograph
it will come out pure white, with no chance of any detail at all (I know
I have
tried).

The main reason why I rarely shoot IR in the winter months here in the
UK is that I find that there are no leaves on the trees and only grass
for the
green vegetation, couple with the white sky's makes for dull images
IMHO.

Also if you use HIE without any IR or Red filter you WILL get a 'normal'
panchromatic image.  HIE records the full visible spectrum with extended
areas into the UV and IR parts of the spectrum.  I believe somewhere
I might have the spectral sensitivity curve of HIE though I have not
seen
it for a while.  In fact it is actually more sensitive to UV than IR if
I remember
correctly.

I Hope this helps with your understanding of HIE.

Jason Revell


 ----------
From: Anthony W. Maw
To: infrared@xxxxx
Subject: Re: FS Wratten #87 (IR) & #25 (red) Gelatin Filters
Date: Friday, 16 January, 1998 5:47

Don't bother shooting in overcast conditions because there is
practically
no IR radiation around.  You may want to shoot without the red filter
and
then you get just regular grainy black and white images.

HIE is sensitive to UV, blue and IR only so you won't even get
panchromatic images on it.

Gregory S. Smith wrote:

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