Lens apparatus, image pickup apparatus, processing apparatus, camera apparatus, and storage medium

A lens apparatus includes an aperture stop, configured to form an image via the aperture stop and detachably mountable to a camera apparatus, a storage storing correction data for correcting image data obtained by image pickup by the camera apparatus, with respect to a light amount distribution in the image; and a communication device configured to transmit the correction data to an external apparatus. The correction data includes a coefficient of an n-th order polynomial (n is a non-negative integer) with respect to an image height, which corresponds to each of a plurality of states of the aperture stop. Minimum F-numbers at a wide angle end a telephoto end, focal lengths at the wide angle end and at the telephoto end, and F-numbers corresponding to the correction data are appropriately set.