Re: KODAK EKTACHROME IR FLIM

[Jason Revell <jason.revell@xxxxxxxxx>]

>W-J may have some ideas about this. Lee Filters in the UK can make one to
>order, but it will cost about UKP 50.00. SRB Film Service in the UK are
>currently waiting for the material to make me one in Cokin A size (for my
>20mm Russar) but are not sepecially hopeful of getting any at the moment.
>After getting a Lee P size one a few years ago, I really don't want to pay
>that much (or anything like it) again. I'd rather pay for a glass one!
>
>One thing that has had me wondering- can you create a near substitute for
>the dark yellow #12 by simply putting two ordinary yellow (#8) filters
>together, or am I on the wrong track totally?
>
>Joe Berenbaum

I am afraid you are on the wrong track.  Using the two yellow filters at the 
same time
will not affect the light in the same manor as the dark yellow filter.

The dark yellow filter will block more of the spectrum which is what you 
need to do,
the doubling up of the filters will not block as much of the spectrum only 
more light,
The only reason that it looks darker is the fact that the transmission of 
the filter will be
heavier, i.e. if only 66% of light gets through one filter only about 43% of 
the light gets
through both filters but the light will still be the same section of the 
EMS.

What I do instead of using my P series filters is buy one size between all 
my lens
(or the widest angle) and then use step-up or down filters to match the few 
different
lenses I have. This provides a cheap alternative even if a bit annoying.

jason.revell@xxxxxxxxx
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