Are circular polarizers as good as linear?

Discussion in 'Medium Format Cameras and Accessories' started by Ric Trexell, Jun 21, 2011.

  1. Ric Trexell

    Ric Trexell Member

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    I bought a Pro Master polarizer filter a few weeks ago and got the second test film back today. It is a 77mm used on an RB67 (127mm). I noticed the first time I tried it that turning it just didn't seem to darken up the sky like my polarizers that I use on 35mm. I don't like to crank the thing to the darkest spot anyway, I usually go about half way as I don't like these pictures you see on a beach with the sky looking like a storm is coming it. Anyway, about all I can say is that it does seperate the clouds a little, but no much. This is probably not the right forum for this question, but it is one of those questions that could go anywhere. I know that my manual focus camera does not need a circular but that was all they had. Is it the fact that it is a Pro Master filter and not a Hoya or Tiffen that is the problem or that it is not a linear? Thanks. Ric.
     
  2. CGW

    CGW Member

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  3. bsdunek

    bsdunek Subscriber

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    As a cheap person, I buy a lot my equipment used. My take has been, linear polarizes stronger than circular, and, good name brands are stronger than no-name generic brands. This of course, is very general and unscientific.
    I tend to buy good name brands and use linear,as I have no cameras that need circular. Just IMHO.
     
  4. bobwysiwyg

    bobwysiwyg Subscriber

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  5. Ole

    Ole Moderator Staff Member Moderator

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    Circular polarizers are linear polarizers with an additional layer that depolarizes the light so that the in-camera sensors work accurately.

    Like linear polarizers, they come in various qualities - some are better than others. Apart from that (and price), there is no difference.
     
  6. Jeff Kubach

    Jeff Kubach Member

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    Also the polarizers work best at a angle to the sun.

    Jeff
     
  7. lxdude

    lxdude Member

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    I stay out of the linear vs. circular debate-too polarizing.
     
  8. Tim Gray

    Tim Gray Member

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    I hate to be pedantic, but they don't have a layer that depolarizes the light. They have a layer (a quarter wave plate) that circularly polarizes the linearly polarized light. Circularly polarized light is still polarized. And that's why they call it a circular polarizer filter.
     
  9. PhotoJim

    PhotoJim Member

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    My experience is that the polarization is identical between them. In theory a circular polarizer could have more flare issues than a linear one, but I've not really seen that in practice (nor have I specifically tested for it).

    If your camera has TTL metering and/or autofocus, circular is the best way to go. If you want to use linear, you can, but you should use an external meter and focus manually.
     
  10. John Koehrer

    John Koehrer Subscriber

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    The end result's the same. If there's a possibility you may have a camera with an internal meter at some point, it won't hurt to use the circular.

    Promaster is a buying group/importer. Dealers have to become part of the group to take advantage of the lower prices they offer. Almost everything they sell carries their name. Some items are good, some OK and some leave a bit to be desired.
     
  11. polyglot

    polyglot Member

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    If there was a lot of haze (which may not be obvious to the naked eye at all) or you were facing mostly towards or away from the sun, no polariser will have much effect because that light is mostly unpolarised. They have their strongest effect about 90 degrees from the sun.
     
  12. Ole

    Ole Moderator Staff Member Moderator

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    To everything but another quarter-wave plate, circularly polarised light is indistinguishable from unpolarised light. That's why a circular polariser will allow beam splitters to work as intended.
     
  13. pityacka

    pityacka Member

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    I thought the peron posting the origininal query ,mentioned he was using a Mamiya RB67, so there is no internal metering etc in the camera. He should be able to use a linear polarizer.
     
  14. Ric Trexell

    Ric Trexell Member

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    Thanks for the replies.

    It sort of looks like the problem is the Pro Master filter, vs. the circular or linear type. I should have mentioned that I only have the WLF and use a handheld meter. To those that aren't familiar with the RB, it is a manual focus so the type of filter doesn't matter. The 90 degree to the light source (sun) is understood. The old rule of thumb is to make your hand like a gun and point your thumb at the sun and where your finger points is the best angle. The filter is okay but I would like for it to go just a hair darker. I took some shots of a house and it did bring out the clouds but just a little more would have made it better. Ofcourse a home darkroom or custom printing would help some too. Oh well, the thing was not cheap, I think it was around $70. Thanks again. Ric.