Re: 87C or 25A

[Eckhard Stephan <eckhard.stephan@xxxxxxxx>]

thunder cat wrote:
> 
> hi again
> 
> i`m not sure if
> this particular filter stacking question
> has been asked, i`m in a situation where i cant get any thing above a 25
> filter
> so would it help if i put
> a polarizing filter with it?

With Konica IR: No. Konica IR has quite an erratic spectral sensitivity:
There are only two peaks of sensitivity in the near ultraviolet to
blue/green region and another one in the orange-infrared region. The
firmer is completely blocked out by the red filter, leaving you with the
film's sensitivity in the orange to infrared part. Unfortunately normal
polarizers have almost no effect on infrared radiation, which means that
in the case of Konica there would be only some (practically negligible)
effect on the little amount of orange to red light recorded by the film.
With Konica IR, a polarizer will work like a neutral density filter: It
will only slow down your effective film speed without changing the image
character at all.
With Kodak HIE, however, a polarizer makes sense, although you may
achieve a similar effect by simply using a dark filter (if you can get
one....).

Hope that helps,

Eckhard

-- 
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*          Eckhard Stephan             * 
*          Freiburg (Germany)          *
*     eckhard.stephan@xxxxxxxx         *	
*   http://www.eckhards-photobox.de    *   
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