Re: KODAK EKTACHROME IR FLIM

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

On  9 Jun 97 at 6:37, George L Smyth wrote:

> Stanee Rae Pettit Murray wrote:
> > 
> > At 11:44 PM 6/6/97 George L Smyth wrote:
> > >
> > >Do your own testing with your own filter.  I had problems with my first
> > >roll because my filter did not cut off sharply enough.  My bracketing
> > >centering around EI 200 resulted "usually" in properly exposed slides.
> > 
> > EI400 worked fine for me on this one roll.  Have you tried the new E-6 IE
> > slide film, or are your exposures based on the old process film?  Perhaps
> > there is a difference?  And what filter(s) were you using?
> 
> This was with the new film.  Remember, meters differ, unmetered amounts
> of IR differ, what we are looking for differ, so we should always do our
> own testing and come to our own conclusions.  I was using a yellow
> Tiffen filter, which resulted in blue skys.  I spoke with Kodak about
> this and we came to the conclusion that the Tiffen does not have a sharp
> enough cutoff.

Not sure what is ment with 'sharp cutoff', but very few
manufacturers offer a medium yellow Wratten #12, and the more common
yellow #8 and orange #21 are not recommended. 
Btw, it is also interesting to note that in older books #12 is referred
to as 'minus blue', with an odd transmission of 3% at 300nm. Not
sure whether it has any influence on the final image, nor whether
this is a pecularity of gelatine (there were no other filter
materials in the early days I believe, right?). 


- -- 
Bye,

Willem-Jan Markerink


      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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