A media sensor for an image forming apparatus is operative to sense and distinguish opaque, transparent or no media in a media path. In one embodiment, an optical source and detector are positioned on opposite sides of the media path, at an acute, non-zero angle with respect to a direction normal to the media path. In other embodiments, an optical source and detector are co-located on the same side of the media path with an optical barrier between them, and one or more reflective surfaces positioned on the opposite side. With no media in the media path, the detector receives a readily detectable amount of optical energy emitted by the source. For opaque media, the detector receives very little, if any, optical energy emitted by the source. For transparent media, the detector receives a level of optical energy between that in the cases of opaque media and no media.