If I'm honest, I've always relied on established brand manufacturers such as e.g. B&W or Rodenstock set. Although I also have a few filters from Kase and K&F in my inventory, I didn't really have Asian manufacturers on the screen when it came to filters.
And that's exactly what K&F wants to change with the Nano-X Pro series.
K&F has meanwhile gained a pretty good reputation in the circles of photographers and this is not least due to the very interesting price-performance ratio which K&F products usually offer .
And now K&F seems to be reaching for the stars and with the Concept Nano-X PRO series they also want to reach the part of the customers who rely on high-quality products and are willing to dig deep into their pockets accordingly.
I tried to find out whether this works with the Nano-X PRO CPL polarizing filter.

As already mentioned, K&F wants to reach the pro users with the Concept Nano-X PRO series and they usually rely on filters from well-known brands and then charge a correspondingly high price for them.
And that K&F is quite capable of producing good filters, I could already see that when trying out the magnetic set and also some plate filters. Of course you had to show a little willingness to compromise here and there, but that was quite bearable, especially given that the filters had previously been in the cheap segment.
This looks completely different with the Nano-X PRO series, here K&F has to deliver unconditionally if they want to do justice to the price.
And yes, they do... starting with the materials, the processing and the quality of the coating, with the Nano-X PRO series, K&F no longer makes any compromises and shows what is technically possible. Gone are the days of stiff threads or seized filters! The ultra-precisely manufactured brass mounts of the Nano-X Pro series run butter-soft and convey the feel of a Peter McKinnon Polar Pro filter. No, that's not blasphemy, comparing these outrageously expensive premium filters with a K&F product. Quite the opposite, it actually
shows only very clear what the engineers at K&F are capable of if you give them free rein

to the filter itself...
I don't want to go into too much detail about the function of a polarizing filter here, that should actually be clear and also the fact that the polarizing filter is one of the filters whose effect cannot be added later in post-processing. It is therefore often said that a polarizing filter is the first and often the only filter that you really need.
The K&F CPL polarizing filter from the Nano-X series tested here plays in a qualitative league with the established brands and must don't hide behind them in any aspect. You don't have to compromise in any category here, really in any. I've never had such a good polarizing filter in my hands, and I'm saying that even though I have an outrageously expensive polarizing filter in stock, both from Rodenstock and from Kase.
The K&F runs so smoothly as if ball bearings were installed and thanks to the milled, really non-slip edge, the filter can also be gripped very well when turning. Of course, an attached lens hood makes it difficult to turn the filter, but that's not a fault with the filter! This is the case with every adjustable filter and many of my lenses have a kind of window in the lens hood for exactly this purpose, through which you can access the filter and adjust it without having to reach through the lens hood from the front.

The K&F also plays at the highest level optically and I could not find any negative effects on the finished picture. It does not visibly distort colors, nor does it significantly increase susceptibility to flares and ghosting. The only noticeable difference, the K&F eats a few more EVs of light, like my Rodenstock polarizing filter, and the tint is about the same as my Kase polarizing filter.
That is of course a matter of taste and one likes very translucent filters and the other likes it to be a little more tinted. Therefore I weigh this point, which K&F does not see as a negative point on the subject of packaging

...
Personally, I prefer a narrow, light plastic case, like these super noble magnetic closure bags used by K&F, but even there you can see the innovative strength that prevails at K&F and the incredible value that K&F places on details. Since I like this kind of thing very much and place a lot of value on small, useful details, K&F already gets a few bonus points from me for the packaging.
If there really is someone who uses the box as a picture frame, as K&F intended, dare that To be honest, I doubt it, but ok, the idea is very nice and a picture frame support that can be folded in origami style is in the box under the filter and cleaning cloth, already in summary

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Uncompromising, from start to finish, so that with the K&F Nano-X Pro, you don't need to ask yourself whether there might be a better filter, just how to explain this issue at home in the most gentle way