In photography and videography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path.
(Lens Filters) Attached to the end of the lens to achieve certain filter effects.
Leica X1 with adapter tube and lens hood
My finished, machined and painted adapter tube. I ground down a Nikon UR-E8 adapter tube until it was almost flush with the X1 lens. Then I added 52mm filter threading.
I could only find a 49mm lens hood, so I had to use a 52-49mm stepdown adapter to put it on, but I can use a circular polarizer, the step-down adapter and the hood at the same time with no vignetting.
Fuji X100 DIY lens hood and polarizer configurations.
49mm filter ring (glass removed), polarizer, silver ring from camera, 46mm lens cap.