About filter reflection factors....

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

Hi gang,

This thought just struck me with my between-the-film-rail #87C
filter experiments: I wanted to use the remainder of the film for IR flash 
photography (it's raining cats and dogs for the last couple of days), 
but I can't trust the OTF flash sensor (On The Film) to read the same 
reflection as it would off the film itself.
So the EOS-guidelines I extracted from German literature might not 
apply in my case, and whatever calibration I might come up with, it 
is probably not valid for anything else than my BTFR (Between The 
Film Rail....;-))) experiment.

And I just realize that using another #87C filter in front of the 
flash screws up any calibration even more....the OTF metering is 
based on reflected *visible* light (or a combination of visible/IR), 
not on reflected IR only....

Cute problems....8-))

So what I need is the spectral reflection coefficient of HIE, as well 
as the spectral sensitivity of the OTF flash sensor. That isn't much 
to ask, is it? <grin>

Guess I will need several films to tackle this experiment completely....8-))

--
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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Topic No. 8