K&F’s build quality has been second to none in the last several years. They’ve created a series of extremely high-quality filters using very slim precision machined brass rings ( brass is a much better material to use for this purpose than aluminum. It’s much less likely to strip threads or to cross thread) and excellent optical glass.This filter is no exception. It has absolutely no optical distortion whatsoever. It filters UV and pretty much nothing else I think it has about a 99.9% visible light transmission.Most people use UV filters to protect their lenses but it’s also helpful to filter out UV light for photographic reasons. It can help to increase the life of your camera sensor and prevent distortion in the images.The anti-reflection coding on this is extraordinary. This competes well with my expensive high end German filters that cost up to four times as much money.This filter is slim enough that it should not interfere with the image or create any vignetting even with wide-angle lenses.This is my review for the UV filter but honestly every K&F filter I have purchased has been extraordinary.Look at the photo and see if you can tell any difference.