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Linear and Circular Polarizers on EM1

Discussion in 'This or That? (MFT only)' started by Phocal, Sep 2, 2016.

  1. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    Ok, I am about to drop a nice bit of money on a polarizer for my ZD 150mm ƒ2.0. It is 82mm, so the lenses I use it on will be limited. There are two reasons I want to get one.

    1. To allow a faster aperture at the airshow when trying to blur propellers. Last year I was well into diffraction when at 1/250 or lower shutter speed. The polarizer will block some light and help with reflections off of the planes.

    2. To help with the blue or green colored reflections I will sometimes get off of gators when I photograph them.

    So, anyone using both or either on an EM1? Looking for any advantages and disadvantages people can come up with when deciding which to get. This will be used with PDAF only and either in S-AF or C-AF, if that makes any performance differences. Any and all advice is welcomed.
     
  2. piggsy

    piggsy Mu-43 All-Pro

    It sounds like you may want a neutral density filter for the first one (I don't use them, but that sounds like a more typical usage case) ?

    The circular polariser CAN help with some kinds of reflections, but it needs to be placed at an angle both to the surface with the reflection on it, and to the light hitting the surface - and once the angle between the reflective surface and your sensor gets shallow enough, the reflections will come back. I'm not sure how easy that is going to be with gators as a subject - depending on how far away you need to be from them you may need to move quite a long way in a large arc to get the right angle to kill reflections on them.
     
  3. Giiba

    Giiba Something to someone somewhere

    279
    Aug 19, 2016
    Burnaby, BC
    A polarizer will fight reflections regardless of your angle to the subject, the angle of the filter is what needs to change and that is why they rotate. Angle to subject only matters in regard to atmoshperic scattering of light and that you cannot control as it is most effective at 90° from the sun.

    Linerar vs cicular only matters with dslrs that use a splitting mirror for AF function. For a mirrorless either will work exactly the same as all the light hits the sensor regardless of filter. Linear filters used to be cheaper but these days the limited volume of them sold seems to be driving the cost up making it easier to find a good price on circular polarizers.

    I recomend looking into Kenko Pro1D filters on ebay as they reviewed really well in the tests Lenstip did and can be found for $50'ish.

    Polarizing filters test - Results and summary - LensTip.com
     
  4. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    You are correct but a polarizer will also cut light anywhere from 1 to 2 stops, spending on the one you buy. So, it can kind of be used as a ND filter while also helping with reflections off of the windows or even the body of the plane. I do want two ND filters, but that is going to have to wait (prices go up when you 82mm filters).

    I guess what I should have asked was what are the differences between using a circular or a linear polarizer. Have only used CP's, so not real sure what the differences are or which I would want to solve my upcoming two issues. Honestly, mostly wanting to correct the gator reflection problem.....but if I an cut some light it will help with airplanes (will not be getting any ND filters for awhile which would be ideal for the airshow, they get expensive for 82mm). Oh............I am really close to the gators a lot of the time, 8 to 10 feet is typical on the big adults.
     
  5. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    Thanks for the link
     
  6. piggsy

    piggsy Mu-43 All-Pro

    Lenstip updated their reviews more recently -

    Polarizing filters test 2015 - Results and summary - LensTip.com

    For subjects that are going to have weird angles and curves in them controlling reflections by cutting out polarised light can still run into some stuff I don't really understand about brewster's angle -

    Polarizer - Wikipedia, the free encyclopedia

    because the reflections are less strongly polarised (according to wikipedia). You can see me running into the effect here on the lawn beetles -

    anyone using cross polarised flash for macrophotography on m43?
     
    • Like Like x 1
  7. Giiba

    Giiba Something to someone somewhere

    279
    Aug 19, 2016
    Burnaby, BC
    Photographicaly there is no difference at all between the two, they do the same thing. If used on a dslr the linear will reek havoc on your auto focus and exposure metering.
     
    • Appreciate Appreciate x 1
  8. Sammyboy

    Sammyboy m43 Pro

    Oct 26, 2010
    Steeler Country
    ..... get the circular, that way you're set just in case you get into a dslr or system that requires one ..... buy once, use on various applications ......
     
    • Agree Agree x 1
  9. Speedliner

    Speedliner Mu-43 All-Pro

    Mar 2, 2015
    Southern NJ, USA
    Rob
    Would that also be the case when using the e-m1 with 4/3 lenses that rely on PDAF?
     
  10. Giiba

    Giiba Something to someone somewhere

    279
    Aug 19, 2016
    Burnaby, BC
    Yup, there is no splitting mirror. All of the light falls on the sensor.

    Essentially dslr's use a polarizer in their mirror to direct most of the light up through the viewfinder and separate some down to the metering+AF.