US Patent 10935761 Large aperture compact lenses

Large aperture compact lens and a camera design using the lens are described. The lens comprises from object to image, three lens groups with a first lens group having a negative or positive power and comprising 3-4 lens elements, a second lens group having positive power and 3-4 elements including an aperture stop, at least one cemented doublet and one positive power lens made from athermic optical material, and a third lens group comprising 1-3 elements.