1. A camera unit comprising: a pickup element; and a lens system in which light rays from a prescribed range of a visual field is imaged onto the pickup element, wherein with respect to a relationship between an image height of respective image portion on an image formed on the pickup element and an image angle of the light lays made incident into the respective image portions, the lens system is configured so that an amount of change in the image height with respect to a change in the image angle is greater at a peripheral portion of the image than at a center part of the image.