I received this product for free as part of the Amazon Vine program for testing purposes. Of course, my following review is still neutral and honest.

At the time of this review, the K&F Concept ND filter with a 67mm thread costs €83.99.

Among the two other K&F Concept products I've tested so far, this ND (Neutral Density) filter clearly stands out. The camera bag and tripod I've tested previously were "okay" for their low prices, but nothing groundbreaking.

This ND filter, however, is in a completely different league! The packaging alone exudes quality. The filter is nestled in a nicely printed cardboard box with a magnetic closure, inside of which is a high-quality (faux?) leather pouch with the K&F Concept logo embroidered on it, also with a magnetic closure. The high-quality filter is finally inside this pouch.

My equipment consists mainly of the Panasonic G9 II, Panasonic's current Micro Four Thirds flagship for photography. During testing, I had the choice of ordering a filter compatible with either my Leica 12-60mm lens or my Panasonic 100-300mm lens, and I opted for the latter. Since I primarily photograph outdoors and in nature, especially in good lighting conditions, this filter is perfect for me.

Screwing it onto the lens feels excellent, and the ND filter's ring, made entirely of aluminum, is of high quality and shows no flaws or mechanical imperfections. Once screwed on, it also features a small, aluminum grip on the ring, which allows you to select the desired exposure level.

The ring rotates freely without any limit or noticeable increments. Instead, there's a scale on the ring itself that indicates the exposure increment. With the filter fully open, you can hardly tell the difference compared to a photo taken without it. You'd have to do some extremely precise pixel peeping to tell whether one photo was taken with a filter or not, and even then it's difficult to distinguish, because unscrewing the filter inevitably changes the angle of view to the subject/comparison photo. That's exactly how a variable-adjustable filter should be—excellent!

What's truly outstanding, however, is the very, VERY wide aperture range of up to 9 steps. I haven't yet had the opportunity to use the filter in the exact scenario I have in mind (e.g., a stream, lake water in the wind, etc.), but in initial tests in the natural surroundings near my home, the filter impressed me practically from the very first second.

The ability to work with considerable long exposures, even in the brightest lighting conditions, to achieve fantastic bokeh effects in my photos without having to adjust the aperture, is simply fantastic.

The only criticism I could offer is the previously mentioned lack of a filter stop for "minimum" and "maximum," in contrast to the filter's free, infinite 360° rotation. This means you always have to keep an eye on the ND ring to ensure it's in the correct position. But as I said, this is nitpicking at a very high level and doesn't warrant any deduction in points.

So, if you, like me, enjoy being outdoors and want to work with long exposure times even in bright daylight, you should definitely get this: a clear recommendation from me.