Linear Polarizing Filters

Discussion in '35mm Cameras and Accessories' started by Ara Ghajanian, Oct 27, 2005.

  1. Ara Ghajanian

    Ara Ghajanian Member

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    Hey gang,
    I was given a B+W linear polarizing filter from a friend who didn't need it anymore (nice friend, huh?). I've read on the B+W site that linear polarizing filters cannot be used on TTL metering cameras. I always thought that that affected autofocus cameras only. I have a Nikon F3 with 80/20 center weighted metering. Could I use my TTL meter with this filter or will I get unreliable results?

    Thanks in advance for all responses,
    Ara
     
  2. Bob F.

    Bob F. Member

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    The light coming off (or through the half-silvered) mirror before it hits the metering sensor(s) gets polarised by the silvering. This will case a linear polariser to mess up the metering. Not sure if the same thing happens with off-the-film metering systems, but basically, if it hits, or goes through a mirror, before reaching the exposure sensors it needs a circular polariser.

    Cheers, Bob.
     
  3. sterioma

    sterioma Member

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    I have a linear polarizer filter (Hoya) which I routinely use with both my Nikon FG-20 (non autofocus) and F100 (autofocus). So far, I have never had any trouble with metering with the filter on (even with the F100!).

    This is based on my experience only, your results might vary :wink:
     
  4. Andy K

    Andy K Member

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    I have two linear polarisers, (one screw mount, one cokin A series). I use both on my SLR cameras, Olympus OM-1 and Praktica BX20, with no metering problems.
     
  5. Ed Sukach

    Ed Sukach Member

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    Polarizing filters, linear or "circular", should, in theory at least, should have NO affect on the measurement of the "strength" of light passing through them.
    I'll access B+W's site to try to see exaclty what is said.
    Possibly a translation error?
     
  6. Ara Ghajanian

    Ara Ghajanian Member

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    I'm surprised it works fine on the F100. I've always read that they give autofocus cameras a problem. I'd simply try the filter out, but it's a 58mm and all my lenses are 52mm so I'd need a step up ring. I'd rather put the money toward the proper filter.
    Ara
     
  7. Dave Parker

    Dave Parker Inactive

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    There have been certain cameras that a linear will affect the metering and the AF functions, in practical use when we were testing when I worked in the foto store, we found that it did not neccessarly have to do with the linear, but with the 2 stop light loss that gave the AF system problems, now these were not extensive tests and almost always occurred on the cameras that had slower lenses. I use a linear on my 9xi and don't have any problems with metering or AF functions....but as sterioma said, your mileage may vary.

    Dave
     
  8. Dave Miller

    Dave Miller Member

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    I would think that both linear and circular give the same light loss, do they not?
     
  9. Dave Parker

    Dave Parker Inactive

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    Yes,

    I am sure your right Dave, but I am sure it had something to do with the way the light transmission occured, as I said, it was not formal testing in any way shape or form, I have a really good article around here about polarisers I will have to dig out, that explains a great many things...I think that it really depends on the cameras itself, I know I have been told many things, then found out in my particular case the information was not as I was told, like many things in photography.

    Dave
     
  10. Ara Ghajanian

    Ara Ghajanian Member

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    Dave,
    So is it safe to say that with a Nikon F3 with Nikkor AI lenses I should be okay metering with a linear filter?
    Ara
     
  11. Dave Parker

    Dave Parker Inactive

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    Ara,

    I would not anticipate any problems on that combination, but I woud suggest doing a couple of test shots and record your exposures to make sure, but I have never heard of any problems using a linear on this combination.

    Dave
     
  12. blumesan

    blumesan Member

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    There is one quick and easy way to tell if the linear polarizer affects the metering.
    Point the camera (preferrably mounted on a tripod) at a light colored indirectly illuminated wall. Rotate the polarizer while watching the metering indicator in the viewfinder. Since the light reflected from the wall is essentially unpolarized, rotating the polarizer will have no effect on the light reaching the lens. If there is any change in the metering indicators then the polarizer is affecting the amount of light reaching the sensor. If you see no change, you're good to go.

    FWIW my Nikon FM and Contax RTS II are unaffected by linear polarizers.

    Cheers,
    Mike
     
  13. blumesan

    blumesan Member

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    There is a quick and easy way to determine if a linear polarizer affects metering. (I have no knowledge re: autofocus)

    Point the camera (preferrably mounted on a tripod) at a light colored, somewhat textured and indirectly illuminated wall. Rotate the polarizer while watching the metering indicators in the viewfinder. Because the light reflected from the wall is essentially unpolarized, rotating the filter will have no effect on the light reaching the lens. If the metering indicators change then the light reaching the sensor is being affected. If the metering stays the same you're good to go.

    FWIW both my Nikon FM and Contax RTS II work fine with a linear polarizer.

    Cheers,
    Mike
     
  14. rosedoodle

    rosedoodle Member

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    I was told that a linear polarizer can interfere with some autofocus cameras- something about splitting the beam(s), whereas a circular polarizer will then correct the split. I got a linear polarizer for my FM3a, and have no problems.