The Heliopan ND filter which is adjustable from 1 to 6 stops of ND by simply turning the calibrated rim on the filter. The Heliopan Vario ND filter is totally neutral in color, it is mounted in a black anodized brass ring that is calibrated for ease in repeating a desired density.
Reviewed by 1 customers
Probably the best Variable ND Filter available. All the other Variable ND filter change the color/hue and destroy the sharpness. There really isn't any comparision. I got the 58mm size because all mys lenses have 58mm and smaller front threads. I keep 58mm stepup-rings and screw-on caps on at all times, as all my filters are 58mm as well. My only complaint is that it does not have front threads. The case is also pretty useless because it is not dust proof. And since this filter is extra thick it is hard to find a case for it. As I mentioned it does not have front threads so stack caps are also out of the quesiton.