Thanks to it's adjustable density control, the B+W ND Vario filter can be adapted to your individual requirements. The XS-Pro mount allows the photographer to set the density between +1 and +5 stops. An index setting allows you to repeat or tweak a density, once results are confirmed for a given subject matter.\n\nNOTE: the index DOES NOT refer to specific f-stops.\n\nYou may combine additional B+W ND filters of fixed value to achieve higher density choices. The ND Vario should be the outermost filter when combined with additional filters. The B+W XS-Pro ND Vario filters are all MRC nano coated, and are offered in sizes 40.5mm, 46mm, 49mm, 52mm, 55mm, 58mm, 62mm, 67mm, 72mm, 77mm, 82mm and 95mm. The XS-Pro Vario ND mount is an EW (extra-wide) design, and should avoid vignetting concerns with most 17mm lenses on a full frame body. As equipment specifications vary greatly, we advise shooting your own tests to confirm results using your specific equipment.