A multi-component system whose aperture stop is located at the front focus so that the chief rays are parallel to the optical axis in image space. For a telecentric lens, the exit pupil is at infinity.

A lens in which the aperture stop is located at the front focus, resulting in the chief rays being parallel to the optical axis in image space (i.e. the exit pupil is at infinity). This results in the apparent size of the object not changing with focus. A true telecentric lens maintains a constant viewing angle at any point across the clear aperture of the objective lens allowing the machine vision system to generate dimensionally accurate images for measurement.

Lens in which the exit pupil is at infinity. Applied, this means that within a certain range of working distances there is no viewing angle error or magnification error associated with features in the image that are at different heights or angles.