The hama 72mm vario neutral density filter nd2 400 has a number of benefits not only does it protect your lens from dust and scratches but it also allows you control the amount of light passing through your lens by as much as 8 exposure stops by rotating the end of the lens you are able to control the amount of light between 1 and 8 stop values that enters the lens for instance f4 instead of f8 for selective sharpness instead of great depth of field or 115s instead of 160s for a smo