The secret of using the cheapies as bore viewers is to have a reflective surface in front of the camera.........the best Ive tried is the white styrofoam bead used as packing......just the level of reflected and diffused light for a good view,and soft enough to push thru with the camera.........without a reflector ,you get what looks like nasty corroded bore is actually the reflections from dust ,fibres etc.......best $12 I ever spent.