The installation of the filter is done the classic way of screwing the filter onto the front thread of the lens. Fortunately, this filter has its edges wider than the typical diameter of the lens which makes it very easy to use and install or uninstall.
The variable light stop feature is done by rotating the front glass element of the filter. You can do this by simply rotating the filter or by using the orange handle which is made specifically for this purpose.
While other adjustable ND filters might exhibit the typical cross or X shape artifact when the filter is close to its maximum light stop. The KF01.1461 does not have this issue, which is great especially for video usage.
Below there is a set of photos taken with the filter set up at different light stops. No visible artifacts or color distortions are present in any of them.
The K&F Concept KF01.1461 variable Neutral Density filter is available for purchase around 55 USD or the equivalent in EUR. For this price you can’t go wrong with this filter as it offers what it promises. The build quality is great, there is no wobble into the rotating mechanism which does the adjusting of light. The surface of the filter edge is also done very well, with well defined white marks and no uneven paint spots.
The mounting system on this filter is very easy to use and basic. You just screw the filter onto the lens thread and that’s it.
In terms of its performance, there are no differences in terms of the photo and video quality while the filter is installed. This shows that the claims of high-quality glass being used on this filter are true. In addition, the various coatings on the glass elements do help with the flare reduction and with the water and dirt cleaning.
The important thing to note about the K&F Concept KF01.1461 is that it does not have the typical cross or X shape present when the filter is close to its last light stop. This is important as many cheap variable ND Filters have this issue and it can pose a challenge for the user, especially for video.
In conclusion, the K&F Concept Variable ND2-ND400 Filter (KF01.1461) is a good camera accessory that does what it promises. It delivers a good optical performance and does not affect the image quality in any way. The variable Neutral Density function works as intended, with a smooth rotating ring that will close or open the light entering the camera lens.