An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max≦2.2.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max≦2.2.

Provided are a rear converter lens and an imaging apparatus capable of achieving favorable optical performance and an appropriate back focal length with high magnification. The rear converter lens RCL consists of, in order from the object side, four lens-groups of positive, negative, negative, and positive lens-groups. In order from the object side, a first lens-group RG1 consists of a negative lens RL11 and a positive lens RL12, a second lens-group RG2 consists of a negative lens RL21 and a positive lens RL22, a third lens-group RG3 consists of a negative lens RL31, a positive lens RL32, and a negative lens RL33, and a fourth lens-group RG4 consists of a biconvex lens RL41 and a negative lens RL42. Here, 0.22<cf/f12<1 is satisfied, where f12 is a composite focal length of the first lens-group RG1 and the second lens-group RG2, and cf is a focal length of the rear converter lens RCL.

Provided are a rear converter lens and an imaging apparatus capable of achieving favorable optical performance and an appropriate back focal length with high magnification. The rear converter lens RCL consists of, in order from the object side, four lens-groups of positive, negative, negative, and positive lens-groups. In order from the object side, a first lens-group RG1 consists of a negative lens RL11 and a positive lens RL12, a second lens-group RG2 consists of a negative lens RL21 and a positive lens RL22, a third lens-group RG3 consists of a negative lens RL31, a positive lens RL32, and a negative lens RL33, and a fourth lens-group RG4 consists of a biconvex lens RL41 and a negative lens RL42. Here, 0.22<cf/f12<1 is satisfied, where f12 is a composite focal length of the first lens-group RG1 and the second lens-group RG2, and cf is a focal length of the rear converter lens RCL.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max2.2.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max2.2.

Provided are a rear converter lens and an imaging apparatus capable of achieving favorable optical performance and an appropriate back focal length with high magnification. The rear converter lens RCL consists of, in order from the object side, four lens-groups of positive, negative, negative, and positive lens-groups. In order from the object side, a first lens-group RG1 consists of a negative lens RL11 and a positive lens RL12, a second lens-group RG2 consists of a negative lens RL21 and a positive lens RL22, a third lens-group RG3 consists of a negative lens RL31, a positive lens RL32, and a negative lens RL33, and a fourth lens-group RG4 consists of a biconvex lens RL41 and a negative lens RL42. Here, 0.22<cf/f12<1 is satisfied, where f12 is a composite focal length of the first lens-group RG1 and the second lens-group RG2, and cf is a focal length of the rear converter lens RCL.

Provided are a rear converter lens and an imaging apparatus capable of achieving favorable optical performance and an appropriate back focal length with high magnification. The rear converter lens RCL consists of, in order from the object side, four lens-groups of positive, negative, negative, and positive lens-groups. In order from the object side, a first lens-group RG1 consists of a negative lens RL11 and a positive lens RL12, a second lens-group RG2 consists of a negative lens RL21 and a positive lens RL22, a third lens-group RG3 consists of a negative lens RL31, a positive lens RL32, and a negative lens RL33, and a fourth lens-group RG4 consists of a biconvex lens RL41 and a negative lens RL42. Here, 0.22<cf/f12<1 is satisfied, where f12 is a composite focal length of the first lens-group RG1 and the second lens-group RG2, and cf is a focal length of the rear converter lens RCL.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max2.2.

An optical imaging lens set includes a first lens element with an object-side surface of a convex part in a vicinity of the optical axis, a second lens element with an image-side surface of a concave part in a vicinity of its periphery, the first lens element being glued to the second lens element to eliminate an air gap, a third lens element with an object-side surface of a concave part in a vicinity of its periphery, a fourth lens element and a fifth lens element of plastic material, ALT being the total thickness of the five lens elements and G.sub.max being the max value of the air gap from the first lens element to the fifth lens element so that ALT/G.sub.max2.2.