Polarizer: Linear Vs. Circular

Discussion in 'Beyond the Basics' started by sbalsama, Apr 28, 2005.

  1. sbalsama

    sbalsama TPF Noob!

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    I'm looking to pick up a polarizer, but I need a good explanation on what the difference between the two kinds are. I have a cheapo circular for my 55mm autofocus Minolta but wish to pick up a decent one for my manual focus 49mm OM Zuikos.

    The only thing I know about the two is that the circular can rotate in its mount and supposedly the linear is for manual focus cameras (and conversely, circular for autofocus). Thank you!
     
  2. Unimaxium

    Unimaxium TPF Noob!

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    Well you've already touched on the main difference between the two. That is, that linear polarizers are for manual focus and circular polarizers are for autofocus. Because of the different ways the two polarize, linear polarizers cannot work with AF systems. For some reason, the focusing system will always want to focus on the filter itself, which it can't do. So if you're going to use an AF camera with the polarizer, you need to get a circular. If you're using a manual focus lens only, then you can use either. As linears are cheaper than circulars, it will make the most sense to get a linear if you're going to be focusing manually. Apart from the AF thing, and the price, I don't think there is much of a difference between the two.
     
  3. SLOShooter

    SLOShooter TPF Noob!

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    The only difference is that the circular polarizer has a "1/4" wavelength shifter on the camera side which circularly polarizes the light so that the light meter can meter it correctly. Most internal light meters rely on polarization for metering.

    The upshot is that if your using AF with an internal meter your probably better off with a circular. If neither of these 2 factors is of concern than save the money and go for a linear.
     
  4. sbalsama

    sbalsama TPF Noob!

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    Hey, okay, so the problem was focussing (and some metering). I really couldn't find out for the life of me, but thanks! Linear it is, because you're darn right it's cheaper :p
     

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