The Hama Vario ND2-400 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 ND2-400 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.