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by Aditya

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I have some pieces of polarizing film from polarization.com, which are reasonably good and not too expensive, but I have some problems with them:

  • They are too thick (only just fit in the filter slots), and probably related:
  • There is significant loss of contrast and haze when a bright light is in the frame
  • There is no anti-reflective coating

The thickness is, in part (I think), because they have an extra layer of quarter-wave-retardation to make them circular rather than linearly polarizing.

I'm particularly interested in using polarizing filters with my fisheye lens, for fun effects with sky and water, so thin, rear-slot solutions are the only option: glass filters would be ideal, but the glass from a normal polarizer is too thick for the rear slot, which is about .5-.8mm thick.

What other options are there? Also, what about ND gels in this format?

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3 Answers 3

Edmund Optics, a Division of Edmund Scientific carries linear polarizing films. In their Edmund Optics catalog they have "Visible Linear Polarizing Film". Their website is www.edmundoptics.com

(Good luck; I also have a Nikon 10.5mm fisheye with which I intend to experiment).

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Warning: this is really more of a comment than an answer, but wouldn't all fit in a comment, so I wrote it here...

The quarter wave plate doesn't contribute significantly to the thickness -- by definition its thickness is roughly one quarter the wave length of light. Visible light has a wavelength between (about) 380 and 780 nanometers, so the quarter-wave plate is somewhere between 95 and 195 nanometers (normally close to the middle of that range).

Most of the thickness is almost certain to be the substrate on which the optical layers are deposited, and a protective layer over the top. At least in a typical case, the polarizing layer and the quarter wave plate will be no more than a couple thousandths of an inch between them.

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I'm afraid the comment by Jerry Coffin regarding wave plates isn't true. Quarter-wave plates for a given wavelength of light can be a huge variety of thicknesses. Even strongly birefringent materials need several wavelengths before they can act as a quarter-wave plate. The cheap, strong, non-dispersive materials usually used in consumer optics are not strongly birefringent, so they are thicker still. They're thin, sure, but they're not microscopic! See this page for more info: Wave Plates

In answer to the OP, I think the partial polarisation of the light that you're trying to exploit is quickly destroyed by passing through the various elements of the lens, so filters on the front of the lens will have a much stronger effect.

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I find my current solution has quite a strong effect regards polarised filtering, but it's the side-effects (lower contrast, glare, worse sharpness) that I'd like to reduce. –  James Nov 25 '10 at 20:42

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