Best Value Filters, some minor issues
K&F Concept (KentFaith Concept) provides some of the best value filters on the market. However, my 6-9 stop VND Filter (Nano-X Magnetic) does have a slight yellow color cast. The filter cost me around $100 ($80 non-magnetic). Fortunately, since the color cast is yellow it can be adjusted in post. However, at $100 I would expect better quality. Additionally, the magnetic VND filters come with a special adapter with grooves to lock the VND in place (to allow you to adjust the stops), however, they don't sell this magnetic filter adapter with grooves on its own so I can't use the filter for any other lens unless it has an 82mm filter thread. Aside from the issues with the VND, the 1/4 black mist, and CPL work well without any major image quality degradation. However, you cannot stack these filters due to vignetting at wider focal lengths (24mm) which is also a bit disappointing.