I've never had a need for a filter on my Mini 3 Pro until today. I was flying around noon with full sun above me and when trying to take a video, the remote screen was all greyed out. I thought my camera was defective, but when I switched to Picture instead of video, it cleared up. When I went in my garage - video worked fine. I finally figured out that the sun was greying out my video. Had not encountered that before. So, what do I need for a basic filter and.. do I just keep it on all the time ??