Long exposures at midnight sun
In midsummer the sun dips behind the trees for an hour and the sky never quite gives up. For photographs this is wonderful and slightly maddening.
A ten-stop neutral density filter turns a bright summer midnight into a thirty-second exposure. The water goes soft, the clouds smear into long brushstrokes and the people on the shore disappear entirely.
Practical notes
Focus before the filter goes on. Cover the viewfinder. Bring mosquito repellent, because the mosquitoes have also noticed that it is still light outside.