RE: EIR tips?

[Jason Revell <jason.revell@xxxxxxxxx>]

>thank for the tips everyone. i have a tiffen #8 yellow (as well as 25 and
>29 reds). i think everyone has been talking about 9, 12, and 15. is the #8
>still going to give me the exciting color shifts?

>interestingly, the EIR sheet mentions cyan, blue, and magenta filters.
>what?

>m


Yes, you will still get the colour shift.

Remember that the reason for the yellow/orange filter is to cut out the
excess blue.  The film (very basically) is sensitive to the full visible
spectrum  and the start of the short IR (approx 280-900nm) , and records
those wavelength's in a different colour.  That colour is the one next to it
(downwards) in the EMS, ie.  IR-Red, Red-Green, Green-Blue and Blue-Blue.

This means that you will still get the colour shift with no filter at all,
BUT half of the image colours will be recording blue.  So by the addition of
a yellow filter you prevent blue light (various amounts by the different
strength filters) being recorded.  This gives you a more useful and more
'natural' range of colours on the slide, as you have removed the blue light
meaning you get one colour on your slide for each colour in the view.  This
is why you images get 'colder' with the lighter yellow filters and 'warmer'
with the orange filters.  Of course your colours will not record as above as
you have to take the subject matters IR reflectance into effect as well,
hence green grass going red/magenta rather than blue, also the same will
happen with different dyes and pigments to different extents (hence me using
the film to aid pigment identification in works of art).

Now of course this is the theory behind how it works, as we all know things
are never that simple, but it's nice to pretend ?

I hope I have not confused to many of you !

Jason Revell
jason.revell@xxxxxxxxx
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