Then, which lens has the shortest focal length?
The shortest focal length, or "ultra wide-angle"lenses, range from 14mm to 20mm, and are followed by "wide-angle" lenses from 24mm to 35mm, and then "standard" lenses from 45 to 70mm, which are similar to the field of view of the human eye.
Secondly, which lens thick or thin has less focal length? Thick lens will have shorter and consequently thin lens will have greater focal length. Because, For a thick lens, the optical path length of the light is more, than for a thin lens, thus, the bending of light will be more in case of a thicker lens. Consequently, it has a shorter focal length.
Thereof, which has a smaller focal length?
Hence, thicker lens has a smaller focal length.
Why thick convex lens has shorter focal length?
Thicker lenses having greater curvature bend the light more and thus have shorter focal length. Thicker convex lenses have more converging power. If the parallel beams incident on the lens are inclined to the principle axis they converge after refraction to certain points to a plane containing the focal point.