There are a number of reviews of various brand CPL filters online.
Breakthrough Photograph's CPL filter always comes out rather favourably.
Here's one example.
The Best Circular Polarizing Filter For The Money Is.... This is the next in my series of filter reviews. I have spent the past few months REALLY getting to
improvephotography.com
I have the Breakthrough 10x ND filter, and love it. Very sharp, colour neutral and very good build quality. It was also less expensive than some other ND filters which performed much worse in the test.
The review that sealed the Breakthrough filter for me was this one.
Is the 10 Stop Neutral Density Filter right for you? Learn all you need to know in The-Digital-Picture.com's review!
www.the-digital-picture.com
The good news is that their quality in filters seems to carry across into their CPL filters (even though this is a review of the 'dark' CPL filter - I would expect the same with their normal CPLs)
Is the Breakthrough Photography X4 Dark Circular Polarizer Filter right for you? Learn all you need to know in The-Digital-Picture.com's review!
www.the-digital-picture.com
Best wishes
Paul