Telecentric Design
A lens design in which light rays strike the sensor nearly perpendicular across the whole frame rather than at increasing angles toward the corners.
In depth
Digital photosites sit at the bottom of small wells, so light arriving at a steep angle is partly blocked, causing corner darkening and colour shifts. Telecentric designs keep the exit pupil far from the sensor so rays arrive straight, which is why some legacy rangefinder lenses that were superb on film show magenta corners on digital bodies.
Examples in practice
A Micro Four Thirds system was designed telecentrically from the start, so its wide lenses show minimal corner colour cast.