>>2971353-I put the heaviest filter on last, which is usually the 10 stop. This helps a lot with the calculated exposure time because I can just multiply my time by 1000 to get the final exposure time.
-When going beyond 10 stops, add an extra 10-20% to the calculated exposure time.
-ND filters are really fun to use in crowded urban environments to give a desolated look to scenes because with long enough time all the people and moving cars vanish.