Filter is nice and I would recommend this product

Alongside its new upcoming ND and CPL flagship filters, the UV filter is another great addition to the new Nano-X PRO Series from K&F. This is a fantastic addition to any camera setup as it reduces haziness and blue-ish cast. Some UV filters get backlash for actually causing other strange artifacts in images such as distortion or discoloration, but this filter does not negatively affect the image quality at all.

Overall, I really recommend you get something like this for your camera. No, it won't reduce the image quality, and it'll actually be a lifesaver as it enhances the image quality and it also offers a level of protection for your lens! Replacing a UV filter is much easier than replacing the glass of your lens if damaged, so keep that in mind.

This is a great filter and fits my sigma e-mount lens perfectly! The packing is fantastic and the case to carry the filter is designed so nicely! Love everything about it!

I've heard varying opinions on the benefits of keeping a UV filter on the end of a camera lens. Many people say it's smart because if you drop the camera, replacing a filter is much cheaper than repairing an expensive lens. I've heard others (particularly professionals) say it doesn't make sense to buy an expensive lens and then put a cheap piece of glass in front of it that will just degrade the image. Those folks say keeping the hood on the lens will provide plenty of protection and if you have an expensive lens, it should be insured against damage anyway.

I've invested in some good Canon L-series lenses so I'm torn on the best approach. I've been leaning towards going without the UV filter, but I still want one if I'm somewhere like the beach and sand or dirt is blowing. So if I'm going to put another piece of glass on the lens, I want to make sure it's high quality and this filter meets that requirement. You can tell when a vendor has put a lot of thought and care into a product and it shows throughout the process. This filter comes in very nice packaging and they provide a high quality case that has a magnetic latch and a nifty ribbon on the side that you pull to extract the filter from the case. This keeps you from having to reach in and possibly get fingerprints on the filter. Great design!

As to the quality of the filter itself, I don't see any aberrations in the image when I use it. This line of filters from K&F aren't cheap so they won't be for everyone, but if you are taking your photography seriously, you should consider this product.

have had many UV filters from multiple brands. This is now one of my favorites. It is exceptionally clear, light weight, and well built. The included storage case is also top notch. I'm going to have the leather flap labeled with a laser. The box converts into a picture frame which is oddly cool.

is reviewed:

"K&F Concept Nano-X PRO Series UV Filter 77mm, Slim Flagship MCUV Filter Protective Filter"

The filter came well packaged in elegant outer packaging. Even this made you curious about the filter with its exclusive appearance.

After opening it, you can see an elegant, very cleanly crafted leather filter protective cover.
This has a folding mechanism that closes safely and cleanly using a magnet.
There is a fabric flag on the side of this protective cover. If you pull on this, the filter comes partially out of the cover via the pull-out function, so that you can remove it very easily and without risk of damage. The filter is packed in a foil bag when delivered. There is also a microfiber cleaning cloth inside the packaging.

After completely unpacking, you can attest to the filter's high-quality and clean workmanship. The filter is free of processing or material defects. The thread of the filter can be screwed onto the lens very easily. The manufacturer specifies 0.01 mm processing accuracy. You can feel this when assembling it. There is absolutely no wobble here. This means that neither wide-angle nor telephoto lenses are affected in their original performance.

Everything works perfectly. The result is impressive.
From now on, my high-quality telephoto lens will be very well protected and, thanks to this UV filter, which guarantees 99.9% light transmission, it is optimally equipped for fantastic shots without any loss of image quality.
The filter has a double-sided 36-layer nano coating. The 0.15% reflectivity of the filter ensures the above-mentioned good light transmission. This reduces stray light very well and prevents further glare. The filter is also waterproof, dirt-proof and scratch-proof. The filter is also extremely light with a very thin brass frame. The type, manufacturer, function and serial number of the filter are noted on this.

Conclusion:
A high-end filter from K&F that impresses with extremely good workmanship and high quality.
Clear purchase recommendation despite the very high price.
I rate the product 5 stars.

Thank you for reading my review, I hope it was helpful to one or two people.

K&F’s build quality has been second to none in the last several years. They’ve created a series of extremely high-quality filters using very slim precision machined brass rings ( brass is a much better material to use for this purpose than aluminum. It’s much less likely to strip threads or to cross thread) and excellent optical glass.

This filter is no exception. It has absolutely no optical distortion whatsoever. It filters UV and pretty much nothing else I think it has about a 99.9% visible light transmission.

Most people use UV filters to protect their lenses but it’s also helpful to filter out UV light for photographic reasons. It can help to increase the life of your camera sensor and prevent distortion in the images.

The anti-reflection coding on this is extraordinary. This competes well with my expensive high end German filters that cost up to four times as much money.

This filter is slim enough that it should not interfere with the image or create any vignetting even with wide-angle lenses.

This is my review for the UV filter but honestly every K&F filter I have purchased has been extraordinary.

Look at the photo and see if you can tell any difference.

This filter came elaborately packaged suitable for gift giving. It also looks great with a gold colored inlay showing its pedigree. Please see the image that’s part of this review for a look at part of the gold colored lettering. It sure does look the part. I tried some test shots with the filter on and off the lens and then did the best pixel peeking I could noting no difference in exposure or color cast. To be fair, I’ve never noticed this with any high quality filter. I’ve never bothered with bargain basement filters because I have no interest in Lomography or its related ilk. The manufacturer says this is thin and it is. Please see the image where I compare this filter with another UV that costs less than half as much. Both seem thin to me. I don’t see how thickness makes that much of a difference because adding any filter will require the removal of this one or you’ll get image quality robbing refractions from between the two filters. I considered using a micrometer to measure the thickness of the lens itself but gave up the idea because I had no way to assure that I’d not scratch either this or another filter I’d use for comparison. In sum, this does work well as a UV filter and it does not in any way alter the images when compared to the same lens without this filter attached.

Objectively speaking, you might ask yourself what exactly justifies this price: a filter that many photographers only use as "lens protection" and whose effect is usually not even visible in the photos. But this line of thought falls short in my opinion.

The Chinese manufacturer K&F (or Kentfaith) is no longer a cheap provider. The product range and thus the expertise includes not only UV filters but also other filters (CPL, NDF, etc.). This filter therefore comes from a group that puts a lot of thought into how to build even better filters. And you can tell that from the packaging of this X-Pro filter:

I ordered the K&F Concept Nano-X PRO series UV filter to use with the Pentax HD DA★ 11-18mm F2.8 ED DC AW lens. I usually use my high-quality lenses without a UV filter. Ultimately, any additional glass in the optical path degrades the quality. But in dusty weather or when it's raining, using a UV filter is definitely a good idea, as you can then rub the filter dry with a cloth or remove dust. If the filter gets scratched, the front lens of the lens is still undamaged.

Now for the filter. The K&F Concept Nano-X PRO series UV filter comes in quite elaborate packaging. The filter is in a pouch, parts of which are even made of real leather. The closure is magnetic. There is a strap on the side of the pouch. If you pull this, the filter slides out of the pouch.
A cleaning cloth is also included in the delivery, and a cardboard stand (?). I don't really understand the point of this. Perhaps it is intended for presentation purposes for dealers?
The filter is "Made in China". There is an importer's address from Germany on the box.

The filter can be easily screwed onto my Pentax HD DA★ 11-18mm F2.8 ED DC AW lens. There is nothing to complain about. The Pentax HD DA★ 11-18mm F2.8 ED DC AW lens is not shaded by the filter. The filter's workmanship is also really good.
I took a few test pictures with and without the filter, and could not see any negative effects. Under normal conditions, I don't think the image result will really deteriorate. Perhaps there are problems with light reflections in backlit pictures when the sun is at the right angle. But that would be a general problem with filters on lenses.

Conclusion:
The filter is really good. The current price of €149 for the 82mm filter is certainly anything but a bargain. Ultimately, it doesn't make sense to buy a lens for around €1500 and then screw a cheap filter onto the lens, which then leads to poorer image quality. I give the filter 5 stars.