Note - the new RF L lenses do not require a filter on the front of the lens to maintain or achieve their weather resistance to dust and moisture. I believe Canon started changing that design element of their L-series lenses when they came out with the version II of the 100-400mm and the 70-200mm. For example, my 70-200mm is the version I (the original EF f2.8L IS) and it is recommended for complete/robust weather-sealing to place a filter on the front. I don't use mine that way and have never had an issue. I have shot in the rain but not heavy elements, nor in an ocean-spray, or fresh-water spray atmosphere - only 'medium' to light rain.I'll bet you a steak dinner that the new RF50/1.2 requires a filter to achieve any kind of water resistance. I think, if memory serves the old EF 50/1.2 was the same.