Quote Originally Posted by mjs1973
Something to be aware of when using a CPL on a really wide lens is that the affect of the filter can change dramatically across the frame. You can get really noticeable gradations in the sky from one side of the frame to the other for example. Some people don't mind this, others hate it. Just something to be aware of.
Exactly why I no longer use CPL with ultra wide angle shots. I find the gradations very unnatural looking and annoying. These days I use a ND grad instead.