A lens system for a camera, the lens system comprising: exactly six refractive lens elements arranged along an optical axis of the lens system, wherein the six lens elements consists of, in order along the optical axis from an object side to an image side: a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element with positive refractive power; a fourth lens element with negative refractive power; a fifth lens element with positive refractive power; and a sixth lens element with negative refractive power; wherein: total track length of the lens system is 6.2 millimeters (mm) or less; on-axis spacing between the third lens element and the fourth lens element is defined as Z a; off-axis spacing between the third lens element and the fourth lens element at a vertical distance Hep from the optical axis is defined as Zh, where Hep = EPD/2, where EPD is entrance pupil diameter of the lens system; and Z a and Z h satisfy the relationship: Z h / Z a > 0.7; and wherein the first lens element has a convex object-side surface in a paraxial region and a concave image-side surface in the paraxial region, and wherein the lens system satisfies the relationship: 1.2 < ƒ 1 / ƒ < 1.6, where f 1 is focal length of the first lens element, and f is effective focal length of the lens system; and wherein F-number of the lens system is 2.0 or less, and effective focal length f for the lens system is 4.4 mm or less; and wherein the lens system satisfies the relationships: TTL / ImageH < 1.9, and TTL / ƒ < 1.4, where ImageH is semi-diagonal image height at an image plane of the lens system. exactly six refractive lens elements arranged along an optical axis of the lens system, wherein the six lens elements consists of, in order along the optical axis from an object side to an image side: a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element with positive refractive power; a fourth lens element with negative refractive power; a fifth lens element with positive refractive power; and a sixth lens element with negative refractive power; a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element with positive refractive power; a fourth lens element with negative refractive power; a fifth lens element with positive refractive power; and a sixth lens element with negative refractive power; wherein: total track length of the lens system is 6.2 millimeters (mm) or less; on-axis spacing between the third lens element and the fourth lens element is defined as Z a; off-axis spacing between the third lens element and the fourth lens element at a vertical distance Hep from the optical axis is defined as Zh, where Hep = EPD/2, where EPD is entrance pupil diameter of the lens system; and Z a and Z h satisfy the relationship: Z h / Z a > 0.7; and total track length of the lens system is 6.2 millimeters (mm) or less; on-axis spacing between the third lens element and the fourth lens element is defined as Z a; off-axis spacing between the third lens element and the fourth lens element at a vertical distance Hep from the optical axis is defined as Zh, where Hep = EPD/2, where EPD is entrance pupil diameter of the lens system; and Z a and Z h satisfy the relationship: Z h / Z a > 0.7; and wherein the first lens element has a convex object-side surface in a paraxial region and a concave image-side surface in the paraxial region, and wherein the lens system satisfies the relationship: 1.2 < ƒ 1 / ƒ < 1.6, where f 1 is focal length of the first lens element, and f is effective focal length of the lens system; and wherein F-number of the lens system is 2.0 or less, and effective focal length f for the lens system is 4.4 mm or less; and wherein the lens system satisfies the relationships: TTL / ImageH < 1.9, and TTL / ƒ < 1.4, where ImageH is semi-diagonal image height at an image plane of the lens system.