i have a camera that is 43mm wide lens. i put a step down ring in it once for my fisheye. the lens is now a 43mm lens right but it has a 43-->37mm step down ring stuck in it, so now its an equivalent to a 37mm lens.
will this screw into the step down ring which is stuck forever?
also, that wouldnt cause any unwanted vignetting or something weird would it?