mwsilvers wrote:
First mounting a polarizer over a UV filter is not recommended. Secondarily, using a polarizer effectively on any ultrawide lens, like the 10-18mm, can be very problematic, resulting in, as an example, unnatural lighter an darker areas of the sky.
Your getting VERY good advice here --- By mistake years ago I did the same thing with a 17-40 mm lens ending up with lots of Vignetting -- When using a Polarizer be selective or you will generate all that unnatural lighter/darker sky