"With this review I am referring to the product ""K&F Concept Nano X-Series UV Filter 82mm Schott-Glass B270 28 Layers MC Super Slim"", which I purchased in January 2023 and now after a few weeks I would like to share my experience.

Background:
As should already be generally known, UV filters are no longer bought for UV protection these days, since no damage from UV radiation is to be expected due to various lens coatings. The UV filters are therefore usually only used as lens protection to protect the front element of an expensive lens against dirt and damage. In the event of damage, it can simply be replaced.
I therefore primarily wanted protection for my Sigma 24-70mm 2.8 Art and my Sigma 35mm 1.2 Art, which have the same filter diameter.

Positive:
I didn't notice any noticeable change in image quality in my tests. Both the sharpness in my test photos was the same as without a filter and I could not see any artefacts or disturbing light reflections. There are also several independent tests that compare the quality of UV filters - the K&F Nano-X does not show any major loss of quality, at least not in these either.
The ribbing on the outside of the filter is also very positive. This is (at least subjectively for me) actually helpful and creates more grip.
The box is also stable enough to safely take the filter with you to the place of use.

Neutral:
What is also often criticized with cheaper filters is the canting of the filter, which means that it can no longer be loosened. With my copy I could see differences between my lenses, but the filter always ran quite smoothly. At least I couldn't find any major problems. As you can hear in the attached video, it makes noises on my 35mm 1.2, but doesn't tilt at all.

Negative:
I didn't notice any points that would make me devalue the full number of points in a different way.

If this review and the attached pictures and videos were helpful, I would be happy to receive positive feedback ("helpful answer" button). If you have any questions, please leave them on the product page. I'll try to answer them there too!"

The best protection for 18-150 mm optics. Delivered on time as usual, with impeccable packaging.

I own several filters from K&F and so far I can only report good things. So for my lenses and areas of application, I give all filters a thumbs up and am happy to order again and again.

Great filter with nice features at a decent price. About 3mm thick. Screws on fine. Hard case. 1 year warranty if you register your product on the website

For Fuji x100v, its easy to install and can be flipped to accommodate a WCL/TCL or a lens hood like in the photo. Will have to actually test it for street photography if its really water and dust resistant.

almost returned it when I found out my lens came with a complimentary $50 Sigma lens UV filter. The optics on it are wonderful, but I'm about to go to Niagara Falls and I imagine I don't want to marry my lens cloth. I thought - why not just test them both under the sink before sending it back? So glad I did! As if by magic, this K&H filter drains and all the water disappears. The free Sigma filter? It sucks the water! And it's hard to get off! If you received a free high-quality UV filter and stay dry 24/7, no upgrade is needed. Do you value versatility in any weather? Buy this now!

Both lenses are Sigma lenses with 2 different brands of UV filters on them. The lens on the left is my 150-500mm with a filter made by another brand. The right is my 150-600mm lens with the K&F filter. The lens on the left looks a little hazy, while the K&F filter does not.

Does not decrease image quality that I can tell. You can feel that it is weather sealed, but I'm not testing it to see if it truly is.

Comes in a plastic case

So far, no complaints.

I needed to protect the lens on my FZ300 and this filter has some good reviews. The overall quality seems very good and the packaging works well when it's larger than necessary. The filter threads well without affecting hood fit, stows or deploys upside down and shows no vignetting at 25mm. There doesn't seem to be any noticeable degradation in photo quality. The glass seems to attract dust and had to be cleaned several times before I could attach it to the camera with no particles on the inside. The outside needs frequent brushing. I'll update if I find more issues in the future, but this filter seems like a good buy.

I'm usually against UV/haze filters due to concerns about their impact on image quality. However, I plan to use my Sigma 150-600 DG DN Sport (Sony E-mount) in fairly harsh conditions such as shorebird photography, surf photography and sports. So I gave in and bought this filter to protect the front element of the lens. In view of the fact that this K&F filter would probably be classified in the "middle class" in terms of price, I wanted to test whether it actually had an effect on the image quality. The attached image of a $20 bill was taken in exactly the same circumstances - 600mm at ISO 100, tripod with no OS. As you can see from the screenshot taken in the comparison view of my image editing software, the image on the right (with filter) is significantly sharper and has higher contrast. I am shocked! I fully expected to remove the filter if I wanted a better picture. Now I can leave it on 100% of the time and just wipe away any spills or dust without worrying about scratching the front panel. Strong recommendation!

Great filter with nice features at a decent price. Got it for around $23. About 3mm thick. Can be screwed on well. hard case. 1 year warranty if you register your product on the website