The Hama Vario ND Filter is a variable neutral density filter with a rotating front lens. It has exposure correction between +1 and +8 stop values possible, and is used to reduce light that is too bright. The Vario ND has various applications, for instance it can allow the photographer to use large apertures while taking pictures outside = backround gets hazy. In the case of exposure times longer than 1/30 seconds, water "flows", if they are shorter, it freezes to ice. Note for Consumers: To avoid vignetting, this filter has a superstructure of the front lens, i.e. the diameter of the front lens is larger than that of the rear lens.