The only test I have available to evaluate a polarizer is to use the polarized light from a current generation LCD monitor along with some non-polarized light to see what the filter eliminates. The setup behind the two images that are part of this review is simple. I placed a DSLR on a tripod in front of a set that included mostly polarized light from a monitor as well as some non-polarized light from an accent light placed to the side. I kept the ISO, aperture and shutter speed constant. In one image I had the K&F circular polarizer set to minimum and the other snap is set to maximum. I also added a histogram of both images to the right of where the computer monitor is in both images. The filter did a good job of filtering out most of the light from the monitor, indicating that polarized light is being filtered. Although my test setup is not a lab and I expect that a real lab like DxO would smile at my test, it is valid in the sense that I have had both good and bad results with it. I also used this setup to test the UV filter included in this kit and didn't notice any change. I haven't posted any images because if there are small differences they wouldn't be visible in a JPEG posted on the web. I rate these two filters very highly. I couldn't see any color cast from either.