The K&F Concept Black Diffusion are excellent examples of a filter type that's a little misunderstood by some people, I think, as to what it can accomplish and do. The filters come in various strengths, and at the strong end of the range can produce results that look like diffusion. That might be useful sometimes for still photography. But the real use for these filters is at lower strength (1/8 and 1/4) for video. When used that way they can both subtly reduce contrast, reduce highlight burn and smooth skin. They won't work miracles. But if your scene is well lit and involves a person speaking to the camera or otherwise being face on to the camera these filters can subtly smooth skin and reduce imperfections. The effect is more noticeable with video shot using log profiles and gamma, to be graded in post production, but shows results even with standard color and camera profiles. I have a whole set of these filters in various sizes just for shooting face to camera subjects, talking heads, etc. There are several manufacturers making variations on this type of filter but the K&F Black Diffusion filters have been outstanding.