My Fader ND has 52mm to the camera and 58mm outside for other attachments. I ordered a round 58mm screw-in lens hood. I also bought a 52mm lens cap, originally for a still camera, I think for Nikon but I am not sure. It holds well.
No vignetting for me because I use it on a 37mm lens with 37mm-to-52mm step-up ring.
No vignetting for me because I use it on a 37mm lens with 37mm-to-52mm step-up ring.