The entrance pupil is usually a virtual image: it lies behind the first optical surface of the system.

This has the effect of changing the entrance pupil shape as a function of angle.

Eyepieces are optical systems where the entrance pupil is invariably located outside of the system.

Specifically, coma is defined as a variation in magnification over the entrance pupil.

In a refracting astronomical telescope the entrance pupil is identical with the objective.

An entrance pupil at infinity makes the lens object-space telecentric.

Another consequence of this design is that the entrance pupil varies in size during the tracking of a target.

The terms Entrance pupil and Exit pupil are used in optics.

Entrance pupil, the equivalent location of the pinhole in relation to object space in a real camera.

The conventional Schmidt does this with a refractive corrector plate which also defines the entrance pupil.

In order to correctly stitch images together without parallax error, the camera must be rotated about the center of its entrance pupil.

The most important function is to rotate the camera around the entrance pupil of the lens, frequently (but inaccurately) called the nodal point.

Most lenses have an adjustable diaphragm, which changes the size of the aperture stop and thus the entrance pupil size.

The entrance pupil of the human eye, which is not quite the same as the physical pupil, is typically about 4 mm in diameter.

They are always listed in the above order since this expresses their interdependence as first order aberrations via moves of the exit/entrance pupils.

In this case the vector space is R with the camera entrance pupil at the origin and the projective space corresponds to the image points.

In this case, the solid angle of interest is the solid angle subtended by the optical system's entrance pupil.

The effect can be quantified using the ratio (P) between apparent exit pupil diameter and entrance pupil diameter.

In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the front of the lens system.

Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter.

This distance replaces the angle u in the preceding considerations; and the aperture, i.e. the radius of the entrance pupil, is its maximum value.

Depth of field can be described as depending on just angle of view, subject distance, and entrance pupil diameter (as in von Rohr's method).

(The entrance pupil of the eye is the image of the anatomical pupil as seen through the cornea.)

All points which lie on a projection line (i.e., a "line-of-sight"), intersecting with the entrance pupil of the camera, are projected onto a common image point.

The goal is for the exit pupil of the VRD to be coplanar with the entrance pupil of the eye.