a camera attachment for providing a low level of diffuse light over a photographic film . this illumination occurs at the time of the exposure of the film . the process may be termed &# 34 ; flashing &# 34 ; and the effect is to make the film more sensitive to light . the attachment comprises an edge - illuminated transparent disc disposed directly in front of a large aperture photographic lens . an additional annular transparent element may surround the disc . &# 34 ; softness &# 34 ; for portraiture can also be accomplished .