Cokin's Z-Pro Nuances Extreme Graduated ND filters are some of the most expensive on the market, but I reckon they're worth ...
Variable neutral density (ND) filters are handy tools for photographers, in that their opacity can be adjusted simply by rotating them. So, why not use them for adjustable-tint sunglasses? Well, ...
Marumi's amazing Magnetic Graduated Neutral Density use science, rather than slots ...