Retro-focus wide-angle objective - has large aperture, small overall size and adequate compensation of aberrations

摘要

The convex surface of a negative meniscus lens and the surface with the stronger curvature of a bi-convex lens behind the negative meniscus lens face the object side. The surface with the stronger curvature of a bonded bi-concave lens behind the bi-convex lens faces the object side and the bonded surface is curved towards the image side. The convex surface of a bonded positive meniscus lens behind the bonded bi-concave lens and the convex surface of a positive meniscus lens behind the bonded positive meniscus lens face the image side. A positive lens is behind the positive meniscus lens. The air gap between the first and second lenses is between 0.4 and 0.8 times the focal length of the whole system.