Help me understand polarization filters

Discussion in 'Accessories' started by alaios, Aug 17, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    Hi all,
    I have a bunch of questions for polarization filters, if someone want to share some of the knowledge

    1. When are useful to be used?
    2. What are their drawbacks? I guess there should be some...
    3 How the sun should be positioned to use them?

    Regards
    Alex
     
  2. Bugleone

    Bugleone TalkEmount Veteran

    210
    Aug 21, 2011
    1).....There are two basic reasons to polarize teh light entering a camera lens...'A' to reduce reflections from something in the scene.....the typical example is to make fish in a pond visible by removing the refelctions from the surface. And, 'B' to enhance the greenery of leaves in landscapes.

    2)......Main drawback is reduction in light causing extra exposure need...this is not so important now in the age of digital capture but used to be of vital importance when quality film speed was only 200 ASA(iso)

    3)......shooting into the sun (or quarter shots into sun) can be diffiuclt, especially with wide-angle lenses (in fact polarizers don't really work very well with wide-angles)...Again, digital allows one to 'suck it and see' by shooting an image and reviewing to see the effect.
     
  3. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Düsseldorf
    Alex
    3) I have read for something like 90 degrees from the sun... which means the sun should be at 90 degress or?

    4) I have the feeiling quite some times that the polarizer is somehow related to the uv filter... or not?

    A.
     
  4. Bugleone

    Bugleone TalkEmount Veteran

    210
    Aug 21, 2011
    Polarizing filters have nothing to do with UV filters which are only used effectively above 6000 feet to eliminate ulatra-violet light in colour film.
     
  5. Benjamin

    Benjamin TalkEmount Regular

    Anyone have any recommendations on which brand of polarizing filter to get?
     
  6. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Hoya has always been a good balance between quality and cost for me.
     
  7. bmg123

    bmg123 TalkEmount Veteran

    310
    Jan 15, 2013
    England, UK
    Since you were interested I did a quick sketch of how polarising filters work.
    Unpolarised light is what you get from the sun and other sources, where light oscillates along all axis of space. Polarisers block light at 90 degrees, so you only get light coming through that is 90 degrees from the position of the polariser, therefore light is theoretically halved. If you have two polarisers at exactly 90 degrees to each other (like in an ND filter), you get little to no light. You can however put 3 filters together, with the middle at 45 degrees to the two others, and still get light coming through because it has switched to a plane that can't be blocked by the other filters, but that's perhaps a bit complex for now.
    Hope that helps!

    pokar.
     
  8. José De Bardi

    José De Bardi Assistant in Virtue

    Aug 31, 2013
    Dorset, UK
    José
    Hi,

    I just joined and was about to start a thread on this subject exactly... This just happened to be the most recent post on the forum so was at the top of the unread list!

    I have read that some have issues getting Hoya 49mm to fit their e-mount lenses...

    As above, I really want a middle if the road balance if quality vs cost filter and want to know its going to fit my lenses before I order.

    Anyone with experience of what works on the Sony e-mount 49mm lenses then would appreciate your insights into what you use...

    Thanks!
     
  9. Tabibito

    Tabibito TalkEmount Regular

    177
    Apr 1, 2013
    I use a Kenko 49mm CPL with wil SEL1855 & SEL35. Other than vignetting on the widest focal length or aperture and some flares when using it at a bright sunny day there's no problem at all. And since Kenko and Hoya filters are from the same company I think it should be more or less the same with Hoya's CPL.
     
  10. José De Bardi

    José De Bardi Assistant in Virtue

    Aug 31, 2013
    Dorset, UK
    José
    Thanks! Just ordered one. Will see how I go!!
     
  11. RT_Panther

    RT_Panther TalkEmount Veteran

    473
    Aug 9, 2011

    Attached Files:

  12. pshojo

    pshojo TalkEmount Rookie

    13
    Sep 5, 2013
    So I have sony 6 with 16-50 lense, is this considered as wide angle? Would polarizer work ok?
     
  13. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    It might be too wide at 16, but if you zoom out a bit you'll be ok. Each lens will be diferent, you just have to find the focal length for your lens that causes issues with a polarizer and not go wider than that focal length.
     
  14. Gandalf

    Gandalf TalkEmount Regular

    59
    Sep 5, 2013
    Normal lens for APS-C is ~28mm. Focal lengths shorter than that are considered wide angle, while FLs longer than normal are "longer." (Most people call long lenses telephotos, which is often technically incorrect as "telephoto" correctly refers to the optical design of a lens, not its focal length.)

    Polaraizers will work fine, but be aware that you will get uneven results with very short focal lengths, as the amount of polarization in the sky (and other subjects) changes depending on the angle to the sun.
     
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  15. Karl

    Karl New to TalkEmount

    4
    Nov 5, 2013
    A pretty good summary on filters: http://www.bobatkins.com/photography/tutorials/digital_filters.html
    Additionally, the consensus seems to be that UV filters serve no optical function on digital cameras (they did on film) but are used merely as protection nowadays. I do have one but only use it in harsh conditions (snowfall, dust, rain) to protect the lens.