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Circular vs Linear Pola


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#1 Alfeo Dixon

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Posted 26 July 2010 - 07:21 PM

I wanted to explore the usage and differences of using a circular or linear pola filter.

Are there any benefits of one or the other? Applications that may call for either?

I'm well aware that auto focus will not work with linear pola filters, but I am not concerned with auto focus.
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#2 John Sprung

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Posted 26 July 2010 - 08:16 PM

Linear polarization has long been used on cameras to make the sky blue and reduce kicks from shiny objects. Circular polarization is used in some versions of 3D projection to separate the images to your eyes using glasses, but I haven't heard of it being used in shooting. If it is, I'll be interested to see what it does.





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#3 William Coss

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Posted 27 July 2010 - 12:28 AM

Using a linear pola on certain film cameras will conflict with the video tap optics. I always took it as a "grain of salt", almost an "urban myth" of sorts.
Arricam ST, just filling in for the day. Couldn't believe this assistant's filter was even on the truck.

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#4 Brian Drysdale

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Posted 27 July 2010 - 02:10 AM

People seem to use the circular on the 3 chip video cameras, although I've used a linear pola on 2/3" cameras without any issues.
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#5 Frank Kistemann

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Posted 27 July 2010 - 05:42 AM

A circular polarizer is essentially nothing else than a linear one with a layer of 1/4 wave retarder plate on it's back (the side facing the lens). Due to that retarder, the plane in which the lightwave is moving, rotates around the wave's axis, so that it would look a bit like a corkscrew. Thus the light could pass through a second polarizer and you won't get any cross-polarization effect, which is important when you work with a system that has another polarizing element like an autofocus or the video assist of some film cameras.



Frank
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