A scatter spot (circle) is a distorted image of a point projected by a photographic lens onto the camera’s matrix or film. These distortions are caused, firstly, by structural factors, i.e. natural imperfection of optics and photosensitive material, and secondly, functional reasons, and above all – selective focus. An image of an infinitely small point can be a point only when it lies strictly in the plane of the matrix or film. If the image of the point is out of focus, the point turns into a blurry spot of rounded shape, the size of which increases with distance from the plane of the ideal focus (see also “Bokeh”).
Formation of a scattering circle. Continue reading