I do a lot of flying flying over water (Lake Geneva) and I desperately need a polarizing filter to kill reflections and darken the sky. These seem to come in sets with other filters I don't really need. I'm in the process of cutting out a polarizing filter from an old pair of polarizing clips (clip-ons). Filter will be feather light, so it shouldn't upset the gymbal. Camera has a ridge running around the top part of the lens surround. Idea is to cut the filter very slightly over size and just wedge it onto the camera. I'll let you know how it goes.