The filter fits my lens well and screws in easily. The lens cap fit on the filter, but the flange on the filter was too large for the lens hood to be used with. Both the polarizing filter and the ND filter rotated smoothly. The polarization filter reduced glare when rotating. The ND filter allowed me to slow down the shutter speed and still get the same exposure. This would be great for giving waterfalls that thin effect, although there aren't many waterfalls here in December. I noticed a purple tint at the darker end of the ND filter, so apparently it's possible to go too far with neutral density filtering. Other than that, I'm happy with the filter and look forward to using it more in the spring.

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.

I picked this up to use with my Sony A6400 with Sigma 30mm 1.4. This is my go-to set-up for taking pictures of the family/kids but wanted this filter to be able to shoot wide-ish open during the middle of the day. So, basically it does exactly what it's supposed to do; there wasn't any noticeable distortion, softening or color changes, and it was able to drop my shutter speed enough to not blow out the highlights. What I really like is the knobs that allow you to change the ND intensity quickly - this is an absolute life-saver for shooting toddlers and young kids, as they are the fastest things on the planet and they're not going to wait for you to change the filter on your camera. The only negative is the need to potentially get a new lens cap as the filter diameter is larger than the lens cap diameter. This is addressed in the description, but it's just something to keep in mind. Overall though, it's a nice filter.

I ordered this K&F Concept 82mm Variable Fader ND2-32 ND Filter and CPL Circular Polarizing Lens Filter to reduce the number of items I carry with me on a landscape shoot.

When shooting landscapes, a neutral density filter can come in handy. It's the easiest way to create that smooth water effect for waterfalls, rivers, and other moving water. And, a polarizing filter helps to tame reflections that would otherwise detract from your images. This filter from K&F combines these two types of filter into a single screw-on attachment.

I ordered this is the 82mm size (so that it would fit my largest lens) and I'll use step rings for smaller lenses. Operating is pretty easy. You use your fingers to rotate the CPL and you use the attached knows to rotate the variable ND filter. Based on meter readings, you'll get about a 6 stop reduction in exposure when the ND filter is set to max and the CPL is adjusted. With the ND set to minimum, you'll see about a stop and a half or so of exposure reduction.

I did not notice the X pattern that appears so frequently with variable ND filters. However, that tends to happen more with wide angle lenses, and a friend is using mine so I wasn't able to test that out. Color rendition is pretty neutral. I did not notice any reduction in sharpness, nor did I experience significant flaring. Unfortunately, it's not possible to use a lens hood when this filter is attached. Also, you need to know that the front diameter of the filter is greater than the rear diameter. For example, if you order the 82mm version of this filter, your 82mm lens cap will not fit. Instead, you'll need an 86mm lens cap. Be sure to look at the chart in the listing so that you know what specific size of lens cap you'll need for the filter size you purchase.

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.

Magnetic Filter Attachment, quick and easy to attach or remove from the camera lens.
THe 1/4 Black Mist filter is fantastic and definitely one of my favorites. The Filter comes with 3 items

1) The Filter Ring that threads on to the lens end
2) The Magnetic filter
3) Magnetic Filter Lens Cap.

Common Question(s):
Can you use the canon lens cap with the Magnetic ring installed (YES)
Can you use the Canon lens cap with the magnetic Filter in place (YES)
Can you use the Lens Cap with the magnetic base without the filter magnetically attached (YES)

Overall, really good quality lens and it is a breeze to install. The Magnetism is strong and the lens cap does not fall off nor does the filter. It has just the right amount of magnetism to keep everything in place.
Very Good Lens and Concept for mounting it to the camera.

K&F Concept's range of filters have never let me down and neither has this variable ND3-ND1000 ND filter.

This filter maintains accurate color throughout the entire range unlike other filters I've used, which is a huge plus since it saves me time in post by not having to mess with color correction.

There is no dreaded "X", even when I intentionally went too far. While I'm not sure the stated range is entirely accurate, it is close enough and provides a ton of functionality, especially given the low price point compared to other filters that offer such a great density range.

I don't experience any vignetting with this filter, which isn't as slim as others I've used. But I rarely get vignetting when using the 18-140mm lens that I tested this filter with so my experience may not be applicable to different lenses.

Stops are clearly marked on the filter, and the adjustment is smooth with a little resistance that offers good control while shooting.

That said there is one thing you should know about this filter - YOUR LENS CAP WILL NOT FIT. I wish they included a lens cap with this filter or at least stated this clearly in the description, because you'll have to either print a new lens cap or buy one that will fit over this filter.

For the 67mm filter, you'll need a 72mm lens cap.

Overall this is an excellent value for a high quality filter. I doubt you'll find another variable ND filter with this range and at this quality for a lower price.

I'm really excited about these new filters that K&F is releasing. The magnetic filter system is a great idea for strong ND filters as I often have to compose my shot without the ND filter attached (because without it it's much easier to see through the lens) and then have to attach it to take the shot . Being able to easily snap the filter onto the front of the lens takes a lot of effort out of removing and reattaching the filter.

The optical quality is excellent, with excellent clarity and hardly any color cast. The processing quality of the metal rings is solid; They are smoothly machined with smooth edges and beautiful knurling. The rotating ND filter rotates smoothly, with hard stops at both ends of the spectrum so you'll know when you've reached the limits.

The magnetic attachment keeps the filter firmly in place, but is probably best used in controlled tripod setups where you know the lens won't be bumped. I definitely wouldn't use this in mass situations where someone or something might knock the filter off, as it wouldn't take much of a jab to make that happen.

No lens cap is included, presumably because the extra weight would make the filter too heavy for the magnets to comfortably hold. K&F makes a magnetic lens cap that I got with another K&F filter set, but it doesn't fit on the outside of the ND filter because the outer ring is larger than 77mm. However, the magnetic lens cap fits on the inner ring, so you can use it when you don't use the ND filter. As far as I can tell, you can't buy the magnetic lens cap individually, only in a bundle with other filters.

The quality of this filter is quite comparable to that of Tiffen. It's reasonably priced and I would definitely recommend it for tripod landscape photography.