This is the variable ND filter and polarizer.
The CPL filter eliminates light reflections on surfaces, cars, water, glass, and also enhances the colors of the sky, leaves, asphalt, etc.

I personally use it for video so I don't lose depth of field by closing the aperture (from f9 I can now go to f2.3 without burning the images due to too much light).

About the image quality. Well, excellent: There are no dominants, no chromatic aberration, no loss of sharpness or the horrible X of gradual ND filters.
I have a very expensive polarizing filter and hardly notice the difference with this one.

Price and performance are top !!!

No problem for daytime use. When using a CPL lens, you need to improve some parameters to increase the amount of light entering to ensure normal exposure. There's nothing wrong with photographing running water and the sea level. Not bad

A very handy variable neutral density filter. I’ve really come to appreciate the quality of K&F‘s filters. They are budget friendly but never sacrifice image or build quality. But I own several dozen of their filters and also some of the other very expensive ones and they have always been able to perform as good or close to the ones that cost several times the amount of money. I wouldn’t put this up against a Hoyer or Schneider-Kreuznach, and that saying somethings since they cost almost $500. Even the cinematic quality ones that professional movie makers use I don’t think outperform this by much of a margin and those things cost thousands.

K&F has really been hitting it out of the park lately with these filters.

The way these filters work with variable neutral density is that they operate using two layers of polarized glass. Then by changing the angle of the polarization you allow more or less lighting. Typically this will create artifacts of a crisscross variety in your photos.

So far this filter has been free of any such artifacts and that’s a pretty amazing to me. My guess is they are using very very small polarizing lenticels. I don’t know. But the filter is not creating any artifacts in the images absolutely sharp and clear.

The build quality of this filter is equal to any that I’ve ever seen. The turning ring is very smooth and there’s enough to get a grip on but it’s still surprisingly narrow so it doesn’t really interfere with your lens. It’s hardly thicker than a single stage filter. The precision machined threads are also smooth and it goes on without any issues whatsoever.

I am definitely impressed that they’re able to produce a filter of this quality at this price. If you’re looking for a variable ND and you don’t have $400 to spend this is a very viable option.

I love that this filter is both an ND and polarizer. This makes it very simple to adjust aperture to the depth of field desired while also adjusting the sky with the polarizer. Having both filters controlled with simple knobs makes the adjustments quick and effortless.

The quality of the glass appears to be excellent. I do not see any odd aberrations with my naked eye. I have had good luck with K&F filters in the past and this one is no exception.

I've picked up a number of filters from K&F lately and they have all been great, well machined, easy to adjust and fit well on my lenses. This one is no exception! As others have said, there is very little color shift with this and at all the settings you get a nice clear view with no variations in brightness across the filter.

If you shoot in places that are almost always brightly lit with direct sunlight, you know that even after lowering the ISO sometimes you still can't reduce the shutter speed enough to get a nice stylistic motion blur on flowing water or waves on a beach. It can also be hard to get the iris opened up to where you get a nice depth of field blur. With this filter going all the way up to ND64 you can easily get the light low enough to take these kinds of shots. While everyone likes tack sharp photos you get with high shutter speed and high F-Stop, sometimes you just want a different look and this will let you get it. From a shallow depth of field shot to focus people on the main subject to a more motion blurred shot to give you the sensation of movement. This can also be used for recording videos. In bright light you often have to turn the shutter speed up which makes the video seem to stutter when you pan. With an ND like this you can pull the shutter speed back down again to get that more "cinematic" look to your videos.

Overall a good filter that I'm really happy with. The only thing is I wish K&F was a little more consistent with their cases. Some filters come in a plastic box, others (like this one) in a little leather slip-case. Regardless of which kind of boxes you get, they really aren't marked all that well so if you carry several it's not always that easy to tell which filter is in which case without opening them and looking. But that's a small thing. All their cases are sturdy and protective as they should be.

So, I got this after watching another content creator on youtube who recommended it to help with creating that blurry background we all love, even in your studio, by cranking up your lighting and then using this filter. I'm pretty new to the whole professional camera type of thing, so I can't explain exactly why it works, but it totally does! I have a ZV E10 (I know it's not considered "professional" but to me it is!) and was struggling to get the kind of look on my youtube talking head videos that I see other people getting with the same camera. This was sort of a 'hack' I guess but it's what it's designed to do for shooting outdoors in brighter light etc. Again, I don't know the technical reasons of what is happening here, but its something to do with shutter speed. I feel terrible for leaving a review for something that I don't exactly understand, but yet, I think maybe that's helpful to know you don't need to be a camera expert to benefit from using this filter because its pretty darn simple. Love it! I feel like I have an even more professional looking shot without having to get a PHD in film school to do it.

Been a big K&F Concept fan, ever since getting my first tripod by them, years ago. And they seem to be stepping it up a notch, over time. For one, their packaging is beautiful, on their filters and accessories, along with the little protective carry bags for them. It's like opening a box of fine jewelry, and enhances the Buyer's Experience. I like to call it, "Power In The Packaging". Very few manufacturers seem to understand that concept, and K&F gets it. Worse still, are those who give you fancy packaging, to dress up a crappy product. But you won't find that here. The quality matches. And, it's magic.
Still trying to figure out how the heck it does that, the adjustment mechanics, how it fades from clear to black. And, the way it knocks off the bright white reflections and smooths everything over, is amazing. Been in the process of rearranging my studio, and putting it all together, so I haven't produced any content with it yet, but I've tested it on some of my cameras and adapters/lens gadgets, and looked at the monitor, sat there mesmerized, adjusting it back and forth, just looking at it, and I'm in love. Can't wait to get it all set up, and put this and my other K&F filters and contraptions to work!

having two filters put together in one is absolutely brilliant! and like all the other K&F concept equipment I have, the quality of this filter is also brilliant, and top notch! This is the first "combo" type filter i have ever had and it is so dang nice to use. I tend to shoot Black and White film mostly, and this filter has been extremely useful for mid day bright sunlight shooting. There is one twist ring that dials in the ND filter, and then another ring that you twist for the polarizing. And the filter is still narrow and streamlined, it is not super thick and clunky to use. I have nothing at all negative to say about this filter, it is really well built, and is easy to use and has one of the nicest protective cases i have ever seen.

I love this variable ND filter. I'm using with a Canon R6 and a Canon RF 35mm F1.8 lens. Fit and finish is impeccable and and it's easy to rotate due to the tabs set at 180 degrees on the filter. Most importantly, I'm not detecting an cross-hatching, which is a common phenomenon on variable ND filters. Also, the lens cap fits securely on the filter, but you can't use a lens hood when using the filter. That isn't a big deal to me, but it's worth noting. This filter has stayed on the lens since I received it. Couldn't be happier - highly recommended. 5 stars.

K&F knocked it out of the park with this variable ND filter. The construction is solid and the adjustment action is smooth on the filter, I have not had any issues, at all, with it. This filter is well worth the cost if you are looking for a new ND filter.

Having a variable ND filter is nice on a sunny day as you can make a lot of little adjustments when trying to get shots without having to constantly be swapping filters. There is a bit of a learning curve for these, but once you get the hang of it, it can really change up the way you shoot. Most of the tutorials for these show you how you can get those smooth shots of waterfalls, however you can use these on pretty much anything and with this being adjustable, it replaces about five to ten regular ND filters.

Great product at a great price.