Image plane in the context of "Aperture stop"

In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. The aperture defines a bundle of rays from each point on an object that will come to a focus in the image plane.

An optical system typically has many structures that limit ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. These structures are called stops, and the aperture stop is the stop that primarily determines the cone of rays that an optical system accepts (see entrance pupil). As a result, it also determines the ray cone angle and brightness at the image point (see exit pupil). Optical systems are typically designed for a particular stop to be the aperture stop, but it is possible for different stops to serve as the aperture stop for objects at different distances. Some rays from object points away from the optical axis may clip on surfaces other than the aperture stop. This is called vignetting. The aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system.

In three-dimensional geometry, a parallel projection (or axonometric projection) is a projection of an object in three-dimensional space onto a fixed plane, known as the projection plane or image plane, where the rays, known as lines of sight or projection lines, are parallel to each other. It is a basic tool in descriptive geometry. The projection is called orthographic if the rays are perpendicular (orthogonal) to the image plane, and oblique or skew if they are not.

In painting, photography, graphical perspective and descriptive geometry, a picture plane is an image plane located between the "eye point" (or oculus) and the object being viewed. It is usually coextensive to the material surface of the artwork. It is ordinarily a vertical plane perpendicular to the sightline to the object of interest.