The darkening you get is 1 stop minimum and 3 stops maximum before a huge purple "X" goes across the entire field of view. Plus, these are polarizers even at minimum setting...and worse, you will have to slightly unscrew the filter to adjust the polarization effect. Polarization flattens human faces which look much brighter with a bit of shine to them. And, if you adjust them during a shot, you are likely to jiggle the camera a bit unless locked down on a tripod etc.These problems are not unique to this make of Vari-ND but affect all of them regardless of price...this one is fairly well built and affordable as they go. Vari-NDs are held up as saviors by DSLR video enthusiasts tired of excusing the lack of ND filters in their hybrid cameras, but it's a false god.So...the only good use for Vari-ND filters is for when you are shooting video and need to change smoothly from 1 to 3 stops exposure reduction without affecting aperture or ISO, don't mind the polarized look, aren't going to overshoot (this one does not have hard stops) and have the camera supported well enough to do the fade without shake.Plausible, but don't spend more on them than this.