does the job

This is the first lens filter I have ever used. I've always read/heard that a good filter can make a significant difference, but until now I've never gotten one. This polarizing filter is very nice! The high-quality construction of glass and metal is easy to see. In my pictures you can see that the filter is attached to my camera, but I was able to attach my lens hood directly to the front of the filter. It has front pickup threads in addition to the rear threads. A really nice feature is that the front of this filter rotates freely. This way I can now easily rotate the tulip hood to the best position without the risk of the filter or hood loosening. I couldn't do that with the hood connected directly to the camera. But does the filter make a difference? I am happy to say that it works very well! I often take pictures through a window and it's very common for the picture to have some "haze" that wasn't there when I took the same picture outside. I took a picture through the window with this filter and was pleasantly surprised to see a picture that looked like I took it outside. I don't know exactly how this works, but it does. Just like polarized sunglasses, this filter "steers" the light in a way that enhances what you see. I am impressed!

Fast delivery, typical CPL packaging in the plastic box, nothing special until then. Very good anti-reflective coating without loss of sharpness with the CPL 55mm diameter D series. I've always lacked that little bit of sharpness, even that was remedied by, among other things, higher-contrast imaging. The picture uploaded here shows a 100% crop on the left without a filter and on the right with a filter. I was concerned here with the sharpness image, made with a Sony a7ii and a kit lens on 65mm with 1/100 f5.6 ISO 800. The second picture shows left without reflection and right with reflection. I didn't want to try if it was scratch resistant.

Everything perfect! I have nothing to complain about. Since I have read many reviews that criticize the detachment of the filter, I would now like to share my experiences in this regard: I have used the filter several times now and can say that the filter can be removed from the lens without any problems. If you feel the filter firmly and don't slam it shut without feeling, then it can be loosened again in the normal way.

I'm used to using filters with the SLR. With the RX100n7, this is only possible with a magnetic filter adapter, eg Carry Speed Magfilteradapter 52mm. The polarizing filter from K&F Concept has proven itself on a hiking holiday in Italy. The image result is very good, the quality of the filter is excellent. Together with the filter adapter you get results like with the big SLR cameras. (It's also due to the quality of the RX100m7) As I said, the image result convinced me that it wasn't a bad buy. Can recommend the K&F Concept D-Series Pro 52mm Slim circular polarizing filter at any time.

I really love the K&F concept filters - they just work...every time. This CPL is both affordable and made from quality glass. There is no vignetting on my 18-140mm lens. And most importantly, there is no color shift like other CPL filters. The threads fit my camera's lens, and the adjustment ring offers just enough resistance to make adjustments smooth and comfortable. This is an excellent polarizer, you will not regret this purchase.

Had previously ordered the filter from KentfaithBasic but unfortunately it blurs my Sony 135GM F1.8 as if it were a much cheaper lens. The KF is sharp, and costs about 2.3 times more at ISO, quite normal and at F1.8 often very desirable in daylight. It's very flat, which in itself is a good thing. The only thing is that the lens cap does not hold as well as it should. Rotatability is ok, steady but a bit heavy. You should get yourself a pull-off tool, without it the filter is often difficult to remove. Filter effect at the lake was ok, but of course not all reflections go away, that would be against physics. So overall I'm very satisfied. Small addendum: The filter has a slight brown/yellow tinge, which is already noticeable in the sky. The corrugation when turning is good. If you have a good lens, you should not skimp on the filter. Possibly better a good one in 82mm and then adapter rings.

These are well made filters, the ring is very small so they don't cause vignetting even on wide angle lenses. These screwed smoothly onto my lens and stayed on securely. These circular polarizers only reduce the light a little, and once screwed on there is an outer ring that allows you to rotate the polarizer to get the best effect. You can use these to reduce reflections from things like water, glasses, and windows. Because it reduces reflections, you can look down into the water, making it look clearer and cleaner. It also helps provide a clearer sky image when taking photos outside. This is the “D” series filter, they also have a “K” series. I'm not sure of the exact difference between the two as K&F's own website doesn't really explain it. From what I can tell the "D" series (these) are a slightly more expensive design with more layers of coatings including water/oil repellent coatings on both sides. They describe these as "waterproof". Definitely well-made filters that do the job.

Good value for money, took a few test shots, it works

For the price it seems to me that it is far above the quality. I recommend it to people who are on a low budget.