Proper Adjustment Circular Polarizer on O-MD E-M1 or E-M5 or E-M10

Discussion in 'Accessories' started by azjsb, Aug 4, 2016.

  1. azjsb

    azjsb Mu-43 Regular

    96
    Sep 19, 2015
    I am using B+W CPL on my 12-40mm f/2.8 and having the toughest time knowing when to stop the rotation of the CPL for max performance when shooting 90 degrees to sun. I usually shoot Apeture priority and could have expected to see my shutter speed or histogram move but it does not in a dependable fashion. Will sometimes see a change of shutter speed but only for a moment, even when rotating slowly. Can anyone add some advise to make using the CPL more dependable as to the proper rotation location? Thanks,
     
  2. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, rotating the CPL will not generally affect the overall exposure...

    The main point of PL filters is to reduce glare and reflections. If there is glare in your shot, rotate until minimized.

    If the sky is in your shot, rotating can make the sky much bluer.
     
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  3. azjsb

    azjsb Mu-43 Regular

    96
    Sep 19, 2015
    Barry13, thanks for that but let me add that the CPL should reduce the exposure by 1 stop when in maximum position and thus, I would think, that would be the best indication that the CPL is maximizing the benefits of the polarization. So, trying to get a solution which doesn't rely on subjective interpretation.
     
  4. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, a polarizer will reduce normal light by 1 stop in any position.

    If the light is already polarized, then the filter will behave very differently.
    Put two PLs together, or a PL plus polarized sunglasses, to see the effect.
     
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  5. azjsb

    azjsb Mu-43 Regular

    96
    Sep 19, 2015
    Barry13, Ah-ha....thank you.
     
  6. alan1972

    alan1972 Mu-43 Top Veteran

    592
    Jun 23, 2012
    Malaga, Spain
    Alan Grant
    You could try setting Auto Exposure Lock and then rotating. This will hold the exposure fixed which tends to make the effect of the polariser obvious, e.g. the sky gets darker as you rotate up to a point and then lighter again. If it is not obvious it probably suggests that the filter is not achieving much for the particular scene. Remember to turn AEL off again once you have decided the position of the filter.

    Or you could achieve something similar by switching temporarily to M mode.
     
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  7. azjsb

    azjsb Mu-43 Regular

    96
    Sep 19, 2015
    Alan1972, I tried the AEL lock and that works well. Thanks for the trick.