All my FX and MF lenses have UV or similar filters in them. Three times have saved them from "bruising" of the front element. For all of my LF and ULF lenses have never attached a filter to the front of any of them, and this going back to the 1970s. Lens caps both front and rear meticulously always used. Never experienced the slightest incident with the front elements on any of these lenses.