The Black Fog filter is designed to give images, especially videos, a dreamlike look by creating a "glow effect" across the entire image. The hard image edges are softened, but the contrast in the dark areas is largely retained. For best results, you must use this filter, especially near the light source. A subtle halo is added around the point of light.

I bought an 82mm diameter for FE16-35f2.8GM.
As for the lens cap, I bought a one-size-up lens cap from K & F Concept's variable ND at the same time (about 600 yen).
K & F Concept and smallrig are the ones who embody the products that camera enthusiasts really want and are not able to reach the itch.
The four corners were clearly projected without being kicked in the ultra-wide-angle range of the full-frame filter-attachable lens (Oh, I'm video-only, so it's 16: 9).
I haven't taken a live-action film yet, but if there is some color cast or the mist is too strong, I will fix it with the camera settings and Da Vinci.
I regularly use black diffusion filters for painting, but the price is cheaper than buying two variable NDs and black mist.
I might buy another one for SEL1018 for APS-C, which is kicked at the wide-angle end by stacking two layers of variable ND and black mist, but before that, I will try it with a step-up ring.

When used on a Nikon D3400 18-55mm it gives great results! Since I was curious to see the result before I buy it, I thought some people would like to see a comparison between a picture with the filter and another without the filter...

It arrived in perfect condition, it is already the third filter I am buying, I am very satisfied with the quality they offer.

K&F Concept is really stepping up their filter game and this one is awesome. This review is for the K&F concept 82 mm black diffusion 1/4 effect with variable ND2-ND32 2-in-1 filter. For this filter, K&F stepped up its packaging, utilizing a magnetic lid box and a magnetic leather pouch. The filter itself is stored in a clear plastic bag, which unfortunately uses an adhesive folding closure (just be careful when removing/inserting the lens to not let the band of adhesive touch the filter). Still, the overall package is much nicer than the plastic snap box with foam cutout, but I can't say if it's more practical or "better" as I feel it provides less protection than the hard plastic snap box. Anyways, on to the filter itself.

The filter looks and feels great. It has a solid metal construction with a premium feel to it. The inner stationary ring has two large areas of knurling and the outer movable ring is fully knurled. One section of the outer ring has an orange metal tab sticking out for easy turning. This particular filter has hard stops built into it for the minimum and the maximum. I am unable to appreciate much or any X effect on my 18-35 mm lens (not that the X effect is typically a significant issue at these lower stop levels from 1-5 anyways). I really like the built-in hard stops though because it lets me know when I'm at the minimum and the maximum and I can make more efficient adjustments instead of just blindly rotating well past each end and going all the way around. The variable ND portion works well, but how's the black diffusion? I'll be honest, it's my first time using a black diffusion filter, but the effects were definitely noticeable between having it vs not having it. It provides that soft cinematic feel and tones down the highlights and contrast. I can't believe I've never used one until now.

The K&F Concept 82 mm black diffusion 1/4 effect with variable ND2-ND32 2-in-1 filter provides premium functionality at a budget price point, especially when compared to the bigger brands. At that point, you're paying extra hundreds of dollars for minor gains in optical performance. If you need the absolute best because it's your profession, then just move on and pay the big dollars. But if you're looking to test the waters or need a strong working filter without breaking the bank, then K&F has the glass you need.

I was actually looking for a plain ND2-32 filter but this one sounded interesting so I gave it a try. Basically the diffusion effect softens the image a bit giving it a more dreamy look. It avoids the "you can count every pore/hair" look that can be kind of harsh when you use a high resolution digital camera. I was kind of hoping the black diffusion would be a separate filter stacked on top of the ND, but it's not. So if you want ND without diffusion you will have to buy a different ND filter to get it.

The machining of the filter is very well done and the filter itself is very thin. I think this is their main reason for combining diffusion with ND, to keep it very thin compared to stacked filters, avoiding vignetting.

As long as you are wanting that dreamy black diffusion look, this filter works great. The level of ND is easy to adjust and doesn't seem to modify the image other than making it darker. No weird color shifts or patterns appear as you rotate it. The high level of ND is great when you want to shoot with longer exposures to get an image blur effect, or to shoot with wide-open F-stop to get shallow depth of field.

The whole thing comes in K&F's fanciest case, leather with a magnet closure. It is a bit more bulky than their plastic cases but looks nice and is much easier to lift the filter out of.

Overall recommended, just make sure you want the black diffusion effect as it's built into this filter. If you don't, K&F have other ND filters without it.

K&F Concept is really stepping up their filter game and this one is awesome. This review is for the K&F concept 82 mm black diffusion 1/4 effect with variable ND2-ND32 2-in-1 filter. For this filter, K&F stepped up its packaging, utilizing a magnetic lid box and a magnetic leather pouch. The filter itself is stored in a clear plastic bag, which unfortunately uses an adhesive folding closure (just be careful when removing/inserting the lens to not let the band of adhesive touch the filter). Still, the overall package is much nicer than the plastic snap box with foam cutout, but I can't say if it's more practical or "better" as I feel it provides less protection than the hard plastic snap box. Anyways, on to the filter itself.

The filter looks and feels great. It has a solid metal construction with a premium feel to it. The inner stationary ring has two large areas of knurling and the outer movable ring is fully knurled. One section of the outer ring has an orange metal tab sticking out for easy turning. This particular filter has hard stops built into it for the minimum and the maximum. I am unable to appreciate much or any X effect on my 18-35 mm lens (not that the X effect is typically a significant issue at these lower stop levels from 1-5 anyways). I really like the built-in hard stops though because it lets me know when I'm at the minimum and the maximum and I can make more efficient adjustments instead of just blindly rotating well past each end and going all the way around. The variable ND portion works well, but how's the black diffusion? I'll be honest, it's my first time using a black diffusion filter, but the effects were definitely noticeable between having it vs not having it. It provides that soft cinematic feel and tones down the highlights and contrast. I can't believe I've never used one until now.

The K&F Concept 82 mm black diffusion 1/4 effect with variable ND2-ND32 2-in-1 filter provides premium functionality at a budget price point, especially when compared to the bigger brands. At that point, you're paying extra hundreds of dollars for minor gains in optical performance. If you need the absolute best because it's your profession, then just move on and pay the big dollars. But if you're looking to test the waters or need a strong working filter without breaking the bank, then K&F has the glass you need.

I got this thinking it was a typical ND filter and completely skipping over the black diffusion part of the description. So I was a little surprised when I put this on my camera and all of a sudden my video looked soft.
The black diffusion part of this filter adds a special effect of softening the footage to give it a dreamy look. It's akin to stretching a thin, mostly see through piece of fabric over your lens. Except this filter gives you a far more consistent and easy to work with image. The black part of the diffusion adds darker overtones to what is otherwise a dreamy image. The example photo in the images really captures it well. If that's a look you like or are going for in your image, then this lens is fantastic.
I did play around with trying to remove the look from the image. The softening effect means you'll need to shoot much higher resolution than you are delivering in in order to sharpen the image without making it over processed. Even then, the dark dreamy look never entirely goes away. So I would recommend only using this filter when you're wanting that type of look.

The ND part of the filter works really well. The different stops are clearly marked on the edge of the filter and it clicks into place nicely. Adding the ND filters gives you so many more options for shooting wide open while in bright light without having to use a ridiculously high shutter speed.

If you're looking for a pure ND filter, this isn't quite it. But if you want an ND filter with the black diffusion to achieve a specific look, this is the easiest and best way to get that effect that I've ever seen.

Black Diffusion filters modify an image adding softness to the highlights. To me the effect is like adding grain to a captured image. The images I took with this filter show increasing grain, at least that is how I can best describe the effect.

Taking a shot without the filter installed, then another with the filter installed but set to minimum effect shows the entire image has a cinematic look. The filter would add a vintage look to a scene. It might be used for a portrait that is simulating an early 20th century look.

The filter comes in a nice box with a leather type pouch. I would rather have a simple plastic box which would be rigid and provide better protection. Fortunately I have some of those plastic boxes for use with this filter.

I will add four images to this review. One is without the filter, one with and set to minimum, one at maximum (mostly black) and one mid setting.

I purchased 82mm diameter for FE16-35f2.8GM.
As for the lens cap, I bought a variable ND lens cap from K&F Concept that was one size up (about 600 yen).
Surprisingly, the convenient things that camera enthusiasts really want haven't been commercialized yet, and it's K&F Concept and smallrig that give shape to products that are within reach.
The four corners were clearly projected without being kicked in the ultra-wide-angle range of a full-frame lens that can be attached with a filter (I'm video only, so it's 16: 9).
I haven't taken a live shot yet, but if there are some color casts or the mist is too strong, I will fix it somehow with the camera settings and da Vinci.
I usually use a black diffusion filter for making pictures, but the price is cheaper than buying two variable ND and black mist.
I might buy another one for the SEL1018 for APS-C, which inevitably gets kicked at the wide-angle end with two layers of variable ND and black mist, but before that, I'll try it with a step-up ring.