I’ve been a fan of K&F Filters for some time now, and have come to appreciate the consistency and the quality of the brand. The majority of my lenses live their lives with K&F UV protective filters on their front element.

Like many others, as the caliber of mobile phone imagery and videography have improved to levels of near professional quality, I’ve begun to concentrate more energy into taking advantage of those attributes, not to mention the portability.

In hand, the K&F Concepts Variable ND2-32 filter does give the impression of quality. In fact, I own the same K&F variable ND filter in a larger size, 67mm. All modern quality optical glass is coated to reduce reflections with K&F following that convention; the 24 multi-layers of anti-reflection coating the seller asserts are appealing and evident to behold.

A variable ND filter works in a similar manner to a CPL, that is, there are two-rings, one that attaches it to a lens and the other that is turned to control the degree of transmission from more or less light, effectively allowing control of exposure. With that in mind, the K&F filter has a comfortable amount of thickness along with knurled edges on one of the rings that allows for ‘sure-footed,’ precise control while being rotated. K&F has not skimped on material or fabrication.

A ND filter, whether variable or not, is used to reduce the amount of light reaching a light sensitive material. In videography, it is generally to follow the convention of a low ISO and a low shutter speed. In still photography, to allow for the use of a wider aperture in bright light situations. In either case, the benefit of the K&F Concepts variable ND filter is that the transitions between minimum and maximum light reduction are not stepped, but infinitely variable between its 2 - 5 stop range. In other words, one can set their camera to the desired settings, then rotate the light reducing transition ring to achieve the desired exposure. Also, adding a second, fixed ND filter to the lens, for example an ND8, effectively increases the K&F variable ND from its 2 – 5 stop range, to 6 – 10 stops, a range of needed light reduction not uncommon when shooting video in bright sunlight.

There are two conventions for stating the amount of ND a filter provides, Optical Density Number, stated in thirds, with each third being a stop of density, for example .3, .6., .9, etc would be 1, 2 and 3 stops. The other is Filter Factor, the convention used by K&F. The Filter Factor rating is based on the actual amount of light reduction between stops, and is related to the inverse square law of light transmittance. Simply put, for each doubling of the FF number, there is a reduction of one stop of light. So, in the case of the K&F Concept ND2 – 32, you have 0 – 2 = 1 stop, 2 – 4 = 2 stops, 4 – 8 = 3 stops, 8 – 16 = 4 stops and 16 – 32 = 5 stops. And so on.

The K&F Concept Variable ND2 - 32 Filter comes from a trusted manufacturer, is high quality in both fabrication and materials, and serves very well the need for which it's designed. That is, by facilitating the means by which the standard video convention of keeping shutter speed and ISO low, can be followed. It does this by precisely reducing the amount of light in brightly lit scenarios. In other words, it allows some control over otherwise uncontrollable circumstances.

This filter is really good quality, both the glass and the general manufacturing. I got the 82 mm filter, and had no problems screwing it in. The fixed piece is a few millimeters thick, so it’s easy to grip and has some textured areas that make it easy to screw onto the lens without spinning the moving part.

The outer rotating filter works extremely well. It’s easy to move, but definitely holds in place well, unlike some other variable filters I’ve had in the past.

My favorite feature is that the ND values are marked on the filter at 2, 4, 8, 16, and 32 stops. It’s variable in between those, but super easy to hit a starting point if you know approximately how many stops of light you’re trying to offset.

The K&F Concept filter is a solid build, with some really good features that you don’t see on every variable neutral density filter. It’s a thoughtful design that’s well-executed.

K&F is always my go-to when it comes to filters. This variable ND filter works very well and I'm happy with the performance. As usual, the build quality is excellent and the glass is clean. No issues here!

I haven’t tested this extensively but the glass looks good and it functions as intended. I’d have to try it on a few lenses and lighting conditions to see if it has any issues so I may update this review later.

The filter fit the P1000 perfectly and worked great for solar photography.

This is a great little ND filter, and is great for controlling light in any video or photo applications. Quality is great, the frame being made of metal. The glass feels great too. The range of the ND filter is 1-5 stops, which is a good range. Very useful for any creator. Reccomended!

This K&F Concept filter is thoughtfully designed and well manufactured out of quality materials. The CNC aluminum rings are a non-reflective matte black finish that easily and smoothly screw into the filter mount of my 24mm Nikkor lens. This filter is a thin mount design and showed no signs of vignetting for this lens.

I like that the five stops of continuously variable ND values are marked on the filter, in stops, with white dots between the extreme ends that are marked for minimum and maximum effect. The adjustment ring turns very smoothly and has just the right amount of resistance so that while easy to turn, it will stay in place where you want it to. The ring only turns between the minimum and maximum points and does not over-travel. The lens mount ring is easy to grip and has some textured areas that make it easy to screw onto the lens without spinning the moving part. The filter adjustment ring has a different texture so it is easy to manipulate by feel without getting the functions confused.

I set up a camera equipped with my 24 mm and this K&F variable ND in place, on a good stout tripod. I did test exposures with no filter and then one shot at each of the demarcated positions. Six exposures taken wide open on aperture preferred automatic. I saw no issues in the final results to blame on the filter. I have owned dozens of filters in my fifty years of professional photography and this is the best filter I have ever used. It reminds me of the very expensive B&W filters that I used to prefer. That said, it is brand new and I cannot predict how well it will stand up to use and age.

I don't use filters often but when I do having an all-in-one variable filter is preferred. Here, K&F delivers an excellent quality ND with a 1 to 5-stop variant. It's a screw-on filter - once on the rotation from one stop to the next is extremely smooth. The 24-layered coating reduces glare and reflections - with additional waterproof coating.

Pros:
360 rotation (can't break)
smooth rotation
waterproof coating
anti-flayer/glare coatings
can use your original lens cap
easily grip and screw on and off

Cons:
unable to use a lens hood

Overall, K&F has become one of the best filter makers on the market and this one definitely does not disappoint. So, if you're looking for a 5-stop neutral density filter, strongly consider this K&F 1 to 5-stop ND filter.

This variable neutral density filter from K&F is a professional filter that yields professional results. It has 24 lasers of nano multi coatings that reduce flare and protect the surface of the glass. It works great. They also make a similar filter that includes a CPL with the variable ND.