Truth be told, I wasn't expecting this filter to be great because K&F is more a middle in the road brand for photography.

Also if there are other reviews using the term "black mist," then they should be educated that's a marketing term coined by another well known brand that rhymes with "Diffen." The actual term for these types of filters are halation/diffusion filters. There are white and black halation filters and this filter would be categorized under black halation filters. Using these types of filters is a stylistic choice as it will REDUCE the overall sharpness and contrast (softens) of your image and blooms your highlights.

Perfect for that dreamy/filmic look if you want to evoke a sense of nostalgia. However, do note that that this effect can be detrimental if you overuse it. Luckily, this is a fairly subtle (weak) halation filter so it will still soften skin tones but won't be distracting. I like it because images are still fairly sharp but I get some blooming. This is a great price for a filter of this quality, which is kinda surprising. K&F is really stepping up their game on this.

Side note: Other manufacturer's have different measurement on the strength of their diffusion but generally 1/2 is good if you don't want to be subtle at all.