I bought this filter to use with an iPhone 17 Pro Max for recording in ProRes RAW Opengate.

I tried several filters from this brand, and this was the only one that gave me significantly better performance in handling bright light, such as sunlight.

I recommend it to anyone who wants quality results and doesn't mind paying a little more for this product compared to, for example, cheaper, lower-end options.

I highly recommend it, and having tested it myself, I understand the overwhelmingly positive reviews. It barely creates any unwanted reflections.

I have no problems filming or photographing.

Since I film in Log mode, I don't see any color distortion and can perfectly adjust my settings. I also can't detect any apparent issues with sharpness.

The price-performance ratio is excellent.

It's very close to perfect, I just wish that they would put a stopper when it reaches the limits... Instead it keeps turning round and round. It's not a big deal but it would make life easier if you did not need to look at the settings and just do it on the fly by the feel.

First off, I use the 58mm filter on a Fuji XT20, an APS-C system, and I use it exclusively for photos. I can't comment on how the filter performs with a full-frame camera or with video.

This is also my first time using an ND filter, so I have no basis for comparison.

The filter saw its first use on our recent vacation, and I can only say that I'm very pleased with the results. For me, as an ND filter novice, the handling is user-friendly; the stepless adjustment has just the right amount of resistance, so I was always confident that nothing would change automatically.

I managed to take some very beautiful shots of flowing water, even in bright sunshine.

This is top-of-the-line K&F. Upon opening, you're greeted with a beautiful transparent wrapper featuring the brand's logo embossed in gold. A lovely faux-leather case houses the filter. The brand seems proud of its product, which is reassuring.

The filter itself was tested on a 24-70mm lens (Sony's famous entry-level lens). I rarely go below 35mm, so there's no issue with the X-axis distortion appearing.

It's incredibly pleasant to use: it glides smoothly and fluidly. The small, ergonomic copper piece allows for precise, infinite adjustments without the risk of leaving fingerprints on the filter. The technical promises are kept; this is a filter I'll take with me without hesitation in bright sunlight.

The only drawback is that it's not possible to mount filters or lens hoods on it. The threading doesn't allow it.

High quality material; great product

I shoot primarily during daytime hours and have been struggling with achieving shallow depth of field in bright conditions while maintaining proper exposure, so this K&F Concept variable ND has completely transformed my shooting approach over the past month. The ability to adjust density from 1 to 9 stops by simply rotating the filter ring means I can maintain my preferred f/1.8 or f/2.8 apertures even in harsh midday sunlight.

What makes this particularly valuable for my video work is how it enables proper shutter speed adherence to the 180-degree rule when shooting 24fps footage, requiring 1/50 shutter speed that's impossible without filtration in bright conditions. The filter rotation feels perfectly calibrated with just enough resistance to prevent accidental adjustment while remaining smooth enough for quick changes between shots.

The optical quality genuinely rivals filters costing twice as much, with no color shifts or sharpness loss that I can detect in my final images. I've successfully stacked it above my Black Pro-Mist filters without any mechanical interference, which maintains my preferred aesthetic workflow. The premium case design with magnetic closure and protective padding demonstrates attention to detail that many established brands overlook. This has become an essential part of my kit for outdoor portrait sessions.

I already use a few K&F filters and I have to say, I'm absolutely convinced by the quality and the results.

They come neatly packaged in a practical plastic box that can also be used for storage.

Thanks to the magnetic mount, the filter is super easy to change once a magnetic ring is attached to the lens.

All in all, great value for money.

I already use a few K&F filters and I have to say, I'm absolutely convinced by the quality and the results.

They come neatly packaged in a practical plastic box that can also be used for storage.

Thanks to the magnetic mount, the filter is super easy to change once a magnetic ring is attached to the lens.

All in all, great value for money.

Below, I'll share my unbiased experience with this item, hoping to help you make a more informed decision about a potential purchase. While I try to be as objective as possible, this is always my subjective opinion.

The 58mm ND2-400 Variable ND filter is an essential accessory for those who want greater control over exposure in their DSLR photography.
This filter, with a variable ND2 to ND400 (1.9 f-stop light reduction), allows you to precisely adjust the amount of light entering the lens. It's ideal for shooting in bright light or for achieving creative effects like silky smooth water or moving clouds.

One of the aspects I most appreciated while using this filter is its thin construction, which helps prevent vignetting even at wide angles, a common problem with thicker filters. Furthermore, the 28-layer Nano X coating ensures excellent light transmission and effectively reduces reflections and ghosting, improving overall image quality.

From a practical standpoint, the adjustment ring is smooth and precise, allowing you to quickly vary the incoming light density without having to change filters. In this regard, I found it particularly advantageous to be able to gradually adjust the amount of light during my photo session.

In conclusion, the 58mm Variable ND filter is a quality product, ideal for amateur and professional photographers who want to experiment with exposure and achieve professional results without complications.

So, for everything written above (based on the item received), my rating is 5 out of 5 stars.