I'm very happy to have been able to test this variable ND filter, which has found its perfect place in my camera bag, whether for video or still photography (especially in bright sunlight).

If you're not familiar with this type of filter, an ND (for "Neutral Density") is a gray filter that reduces the amount of light entering the lens, but without altering the colors or white balance. In short, it allows you to film or photograph with "creative" settings (wide aperture, slow shutter speed) even in bright or very bright light.

This model is described as "variable," meaning you can adjust the level of darkening simply by turning a ring. This is really very practical when the light changes rapidly, such as during outdoor filming in broad daylight.

I tested it on my OM-1 Mark II with a 12-40mm f/2.8 lens and filmed at 1/50s in the middle of the afternoon while maintaining a good depth of field. If I didn't have this filter, I would have had to stop down to f/11 or wider, thus losing all the background blur that looks so good.

One important technical point to keep in mind: below a focal length of 19mm, you're very likely to see a phenomenon called the "X effect" or "X-cross." This is actually a sort of dark cross that appears in the center of the image. It's caused by the interaction between the two polarizing layers of the filter when it's pushed to its extremes. It's not a manufacturing defect; it's a phenomenon common to all variable ND filters. To avoid it, you should stay above 19mm for photography, or 17mm or wider for video.

The optical quality, however, is impeccable: no color cast, no visible loss of sharpness, it's clean.

The multi-layer coating repels water and dust well, and the small orange handle allows for precise adjustments without touching the glass. The threading is very well finished and the whole thing feels very solid.

The only minor drawback is that the filter prevents the use of a lens hood, and you'll need a 67mm lens cap if you want to protect it (the filter, although 62mm, protrudes slightly). Nothing major, but good to know.