The glass in this filter has etched parallel and perpendicular lines that
create four rays of light emanating from every light source point in the picture.
The glass is mounted in a rotating frame so that the orientation of the rays can be
adjusted.
The glass in this filter has etched parallel and perpendicular lines that
create four rays of light emanating from every light source point in the picture.
The glass is mounted in a rotating frame so that the orientation of the rays can be
adjusted.