Lens Hood:In photography, a lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare.The geometry of the lens hood can vary from a plain cylindrical or conical section  to a more plex shape, sometimes called a petal, tulip, or flower hood. These more plex shapes of lens hood take into account the final image's shape and aspect ratio.This allows the lens hood to block stray light with the higher portions of the lens hood