It's a common technique to use ND filters when capturing long exposure photos during the day. The scenario is that you know how long you want your exposure to b

It's a common technique to use ND filters when capturing long exposure photos during the day. The scenario is that you know how long you want your exposure to be, for instance 5 seconds. And your problem is that those 5 seconds will flood your sensor with light. The solution is to use a ND filter.