There are as many creative filters out there for photographers as there are photographic applications, and each new filter to the market promises to do something different or better than the last. The best variable ND filters reduce the light entering your camera, slowing down exposures for expressive movement, or balancing scenes with different light levels.
Variable neutral density filters are my go-to for achieving wide apertures in super-bright situations like the midday sun because I can control the amount of light entering the camera and still create a shallow depth of field. And that's not something I can fix or add in post-production.
