Long Exposure Calculator is a free app that any hardened photographer will find useful the next time they take some digital pictures. It is designed to be used in conjunction with Neutral Density Filters, something which (as any experienced photographer will know) require careful attention to detail. Long Exposure Calculator will help you to work out what the best time/shutter speed will be when you use your filters, and thereby make it just that little bit easier for you to get the perfect photograph.