Re: Workable HIE Speeds

[Ian D Wilson <idw@xxxxxxxxxxxxxxx>]

I've always found Laurie White's rule of thumb for sunny days to be
incredibly useful: 1/125s at f/11 (or equivalent) with a 25 red filter. 
This sets the nominal ISO rating of the film at about 64 in sunshine,
which is pretty workable for wide-angle to medium telephoto lenses.

My own rule of thumb for days which aren't sunny is to measure the
number of stops below full sun for visible light, and then halve it for
IR.  For example, if the visible light is 3 stops below the sunny/16
level, I expose HIE at 1.5 stops below its sunny setting.  This is a
generalisation based on empirical evidence, but I'm always amazed how
good it seems to be.

Maybe other people use similar schemes?

-- Ian.

--------------------------------------------------------------
Dr Ian D. Wilson         |  Email:  iwilson@xxxxxxxxxxxxxxx
Principal Engineer       |  WWW:    http://www.telemedia.co.uk
Telemedia Systems Ltd.   |  Tel:    +44 (0) 1223-477000
Mount Pleasant House     |  DDI:    +44 (0) 1223-578378
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England                  |  Mobile:         0467-473594
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