how does thickness of a lens affect focal length Share with your friends Share 1 Pratyay Ghosh answered this A thick convex lens means the radius of curvature of each of the sides is less than that of a thin lens. Less radius of curvature means higher focal length for a convex lens. -2 View Full Answer Rasi Annanthi answered this If the lens is thick the focal length decreases allowing us to see nearby objects clearly 1