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  1. #11
    RobertV's Avatar
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    Well, you can read that on their web site.

  2. #12

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    Quote Originally Posted by RobertV View Post
    Well, you can read that on their web site.
    Yes.

    But how could it be possible?

  3. #13
    RobertV's Avatar
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    But how could it be possible?
    I do not know. I was informed about this on the Photokina in Köln by Mrs. Summers herself. One of the few new analog things overthere. Well, (X100), GF670W, TMY-2, T200, Fomalux 111, RPX 100/400 and a few other things.

  4. #14

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    Maybe you could ask her?

    It must be marketing talk: either that it is only 1/2 stop, or that it's a polarizer. Both can't be true.

  5. #15
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    Not:
    http://www.heliopan.de/produkte/pola...nsfilter.shtml

    How they do it is another question but maybe it's one of the secrets of a filter company. All made in Schott glass.

  6. #16

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    Quote Originally Posted by RobertV View Post
    Not:
    http://www.heliopan.de/produkte/pola...nsfilter.shtml

    How they do it is another question but maybe it's one of the secrets of a filter company. All made in Schott glass.
    Not "not".

    Yes, they know about light and polarisation.
    That makes it even more of a mystery why they say a polariser can have a 1/2 stop filter factor.

    Polarizers only use glass as covers, to protect the working bit: a 'plastic' foil.

  7. #17

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    With a linear polariser a simple energy argument gives at least one stop of loss. These are circular polarisers though. What is the angular spectrum of the incident light?

  8. #18

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    Quote Originally Posted by Pete H View Post
    With a linear polariser a simple energy argument gives at least one stop of loss. These are circular polarisers though. What is the angular spectrum of the incident light?
    Circular polarizers are linear polarizers. The effective bit is exactly the same.
    The difference is in what happens behind the filter, i.e. after the linear polarizer has done what linear polarizers do.
    Circular polarizers have an additional quarter wave retarder plate, which gives the polarisation vector a push, making it spin around the light's direction of travel.

    So at least one stop for circular polarizers too.

  9. #19

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    It appears this thread has taken a life of its own. How many stops of light the circular polarizer reduces isn't relevant to me because I only need a linear polarizer. I am using manual focus lenses and setting my video camera to manual focus and manual exposure (as anyone half-serious about film does). It's true that I'm mounting my Minolta lenses on top of the camera's inbuilt lens via an adapter but as I don't require the use of the camera's autofocus or metering systems, I do not require a circular polarizer. Correct?

    I'm deciding between the Hoya, B&W I previously listed and this Heliopan:
    http://www.foto-mueller.at/shop/heli...onsfilter.html

    Gotta tell ya..I'm still tempted to go with Hoya..

  10. #20

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    Quote Originally Posted by sherwin View Post
    [...] Gotta tell ya..I'm still tempted to go with Hoya..
    And why not. Should be good.

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