My last trip I used the back scatter flip up lense on my GP. The filter did a great job for what it is intended, however I had a lesson learned. Whe you jump off the boat...bubbles get "Stuck" between the filter and the lense and they will stay there the entire dive. If someone goes under you and you swim through bubbles...they get stuck too. TIP= Flip the filter open, wipe it off with your fingers before you start to video. I had some pretty good footage ruined becaue of this little issue.
Peace~Out
Peace~Out