This is a review of a 77mm K&F Concept Nano-K Series ND2-32.

First impressions are that this is a very well-made filter for the price. The body is machined from aluminum, with a matte anodized finish. The threaded rear ring is nicely knurled. The rotating ring has very fine knurling on the front edge. There are varying sized dots on the edge indicating the number of stops (1-5) of exposure reduction. Numbers would be a little nicer, but the dots are not hard to figure out.

The rotating front element is larger in diameter than the rear. This should minimize any vignetting with wide-angle lenses. However, if you expect to stack filters on top of this, be aware that the thread diameters are different. On the 77mm version, the diameter of the front threads is 82mm.

The filter threads into the lens smoothly with no signs of binding as you often see with inexpensive aluminum framed filters. Once mounted, the front ring rotates smoothly, with hard-stops at 1 and 5 stop positions. The total rotation from the minimum to maximum position is a bit less than ¼ turn.

The 1 to 5 stop range is good for bright conditions where you need a slower shutter speed to sync with fill flash, or a wider aperture to better separate the subject from the background. If you need super long exposures for super silky water effects, K&F makes a variable 2-9 stop version, as well as 16 and 20 stop fixed ND filters.

The stop marks on the filter rim appear to be pretty accurate. Using aperture-priority mode, the shutter speeds were very close to the expected progression. Starting at the 5-stop setting, the speeds were 1/8, 1/20, 1/40, 1/80 and 1/160. And removing the filter yielded a speed of 1/320.

Coloration is the downfall of many ND filters. Through a DSLR viewfinder, this filter seems to add a subtle greenish-yellow cast. Surprisingly, in my test images this coloration is visible only at the lower density settings. By the 3 stop mark, the color balance is quite neutral. Overall, not a bad performance.

Top quality

Perfect and beautiful construction

No X effect or noticeable dominants. Correct for its price.

The filter is of high quality and delivers the desired image.

I ordered a little late and delivered quickly to my vacation spot to compensate for too much sunlight that my Leica could not manage at full aperture. Well I must say that I am pleasantly surprised by the practical side of this filter, the fact of being able to gradually manage the density is a great idea. I still note a slight alteration of the white point which turns a little yellow, which must be compensated digitally on the body, but the rendering is really good and does not alter the optical quality of your equipment. The finish is very good, the screw thread is well machined and attaches without problem to the lens, I would just have appreciated a light gray metal color rather than black black because as it is it stands out a little on my lens.

I just bought this ND filter, and it's really changed the way I take photos. As a photography enthusiast, I was looking for something that performed well without breaking my budget, and this filter fits the bill perfectly.

The biggest advantage for me is its flexibility. There's no need to constantly change ND filters, which is a real time saver when you're out in the field. The fact that it can be adjusted from ND2 to ND32 is super practical for controlling light and shutter speed, especially when capturing moving effects in landscapes like waterfalls or rivers.

The quality of the glass is impressive; there's no loss of sharpness, and the nano coating helps reduce unwanted reflections. The thread is sturdy, and the plastic housing protects the filter well. One small drawback is that it adds a bit of bulk to the lens, so you can't use a lens hood with it.

This filter is easy to use, with clear markings for each ND level and self-locking technology that prevents the black cross phenomenon. It also comes with three individual cleaning cloths, which is a plus.

In short, for its price, this filter is an excellent addition to my camera gear. Ideal for those who want to experiment with long exposures and different lighting conditions without breaking the bank. I highly recommend it!

I recently picked up this Variable ND Lens Filter and I'm quite happy with it. As a casual photographer bordering on semi-pro, I didn't want to splurge on pricier gear, and this filter fits the bill perfectly.

What I love most is its convenience. It's a real time-saver when you're shooting on the fly and don't have time to mess around with swapping fixed ND filters.

The pros are plentiful: the glass is good quality and doesn't seem to affect sharpness, the threading is solid, and the plastic case keeps it safe.

On the downside, it adds a bit of bulk to your lens, and obviously cant be used with lens hoods.

Great for someone like me who likes to dabble in long exposures and varying conditions of outdoor photography.

I certainly wouldn't have expected this quality at this price. The build quality alone is top-notch – the thing feels like it's from the top price range of a luxury camera brand.
Nevertheless, I didn't have particularly high expectations when I first screwed the filter onto a camera.
Working with the filter is a pleasure in itself – but the result completely convinced me. A bit of a tweak to the high end does shift the color spectrum a bit towards green, but that's nothing that can't be corrected in post-production with a click of the mouse.
I've never used K&F filters before – but I'm sure this won't be the last product from them that finds its way into my camera case.
Great!

The variable ND filter is very well made and works perfectly on my Canon EF 85.

I also use it with my RF 50/1.8 with an adapter ring.