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Re: [OM] Polarizers

Subject: Re: [OM] Polarizers
From: Richard Schaetzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 08 Oct 1998 13:39:41 +0200
R.S. Adams wrote:
> 
>  What is the
> practical difference between a circular and linear polarizer? 

An linear polarizer consists of one layer of polarizing foil, which can
be rotated to eliminate polarized light of certain direction. It lets
pass only light of a certain polarisation, this is handy to eliminate
haze, which consists of unpolarized light, flare light (polarized rays
of light of any angle). By cuting out the mayority of straylight your
improving contrast and saturation.    
An circular polarizer has an second layer, which depolarize, "scramble"
the polarisation of the light. This is neccesary if there is any
metering which is sensitive to the polarisation of light
(semitransparent mirrors for light metering and AF)

> Is there
> a difference in the effect produced?  

No, because the film records difference in light intensity and not
polarisation, the "scrambling" doesn´t affect distribution or absorbing
of light through the filter.

> The amount of light attenuated?

No, this is more a property of different quality polarizing foils.

Regards

Richard



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