# uneven polarization



## cid (Nov 9, 2014)

Hi guys, 
on my last trips to mountains I encountered some uneven polarization effect. I was wondering, is there any way how to use polarizer and prevent from this effect? Or do you merge more shots to handle it in post processing?

I have heard many opinions that this effect should be more visible with focal length of 24mm and shorter, but I've seen it in some of my shots with FL longer then 70mm (even in some 200mm shots), am I doing something wrong?


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## Mt Spokane Photography (Nov 9, 2014)

You need to provide more than just general information to get a intelligent answer. 

What brand polarizer, sample photos, camera used, lens used, settings, etc. Don't forget that the best brands are also big targets for counterfeiters, and there are a ton of B+W counterfeits out there that often have issues. Its easy money for those who make them.


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## e17paul (Nov 9, 2014)

Mt Spokane Photography said:


> You need to provide more than just general information to get a intelligent answer.
> 
> What brand polarizer, sample photos, camera used, lens used, settings, etc. Don't forget that the best brands are also big targets for counterfeiters, and there are a ton of B+W counterfeits out there that often have issues. Its easy money for those who make them.



That's a good point. I only buy filters from known camera shops in whom I trust, or Amazon. If buying from Amazon, then I make sure that I am buying from them, not a marketplace seller, even if fulfilled by Amazon. eBay is also to be avoided. In short, I trust no one without a reputation to protect, and who I wouldn't expect to buy direct from the filter manufacturer.


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## lintoni (Nov 9, 2014)

It's to do with the angle your camera is pointing with respect to the sun. Maximum polarisation occurs when your camera is aimed at a perpendicular angle to the sun.

Here's a link for you:

http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm


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## cid (Nov 9, 2014)

Mt Spokane Photography said:


> You need to provide more than just general information to get a intelligent answer.
> 
> What brand polarizer, sample photos, camera used, lens used, settings, etc. Don't forget that the best brands are also big targets for counterfeiters, and there are a ton of B+W counterfeits out there that often have issues. Its easy money for those who make them.



Gear I used is 5D mk III + 24-70 and 70-200 (in my signature  ), both with BW kaesemann filter.

Both filters are genuine, I do not worry about this, both were bought from authorized dealer and also had hologram on case.

Basically is doesn't surprise me to see this effect when I'm using 24-70, it's quite wide on FF and I try to be carefull when using this lens with polarizer. More I was surprised to see this effect when I used my 70-200 with polarizer. Maybe relevant information is, it was in mountains when I noticed it(2000m+)

*What I would like to know is how to prevent this situation of uneven polarization with longer lens?
How to solve this issue? Sometimes the reflection has to be cut with polarizer or colors need a little boost, but sky is then uneven ... do you take more shots? Or do you take a shot with and without polarizer to solve it?*

I'm sorry not to upload any photos, if it's necessary I'll add them later (I'm not on my main computer right now)


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## cid (Nov 9, 2014)

lintoni said:


> It's to do with the angle your camera is pointing with respect to the sun. Maximum polarisation occurs when your camera is aimed at a perpendicular angle to the sun.
> 
> Here's a link for you:
> 
> http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm



thank you for sharing link, it's great page and I went trough it already


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## andrewflo (Nov 22, 2014)

I'm far from an expert with CPL's but I have experienced this same thing. Usually shooting large wide sky scenes at wider than 35mm.

When you have such a wide view of sky, the far left and far right sides of your image are literally in regions of different polarizing effectiveness in regards to their angle to the sun.

In fact, sometime I just look up at the sky with my naked eye and see that different angles of the sky appear different shades of blue. A CPL will exaggerate that.

The solution may be use less CPL or shoot narrower. Ultra wide + CPL can be problematic from my understanding.

Someone please correct me if I'm wrong.


Were your shots at 200mm of distant skies? I don't think the above would apply that the longer focal lengths like that so I'm stumped there.


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## tolusina (Nov 22, 2014)

If I understand correctly, a polarizing filter filters light with a single polarization component, light polarized differently than what is being filtered out gets through, the light that gets through is your image.

If a scene is illuminated with light from multiple sources such as the sun as the primary source with one polarization plus light from some reflective object with a polarization different than the primary such as a nearby body of water, you can only filter one polarization or the other, not both.

Changing your angle of view of a scene can sometimes (don't count on it though) offer a view where the planes of polarization from two sources are aligned, then you can filter both.
Of course changing the angle of view well necessitate a change of position, changing angle and position will change the composition.

Might be that a ND filter or a graduated ND on camera or in post will offer the scene enhancement you seek.
Note that polarizer effects cannot be duplicated in post.


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## Aglet (Nov 24, 2014)

I find I can achieve a similar enough effect, with more consistency and less color-shift, in post.
I only use a polarizing filter when I need to kill specific reflection issues but even then, things can be done in post.
It's my least-used filter.


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