Compact wide-angle zoom lens

Claim 2

A compact wide-angle zoom lens having a plurality of lens components, at least some of which are movable between a wide-angle position and a narrow-angle position, said zoom lens being composed, in order from the object side, of a variator that consists of a first lens component having a negative focal length and a second lens component having a positive focal length, and a fixed third lens component that is positioned subsequent to the variator for increasing its focal length, said first lens component having a negative-positive lens unit arrangement, said second lens component having a positive-negative-positive lens unit arrangement, and said first and second lens components being mechanically moved so as to provide a variable focal length and maintain a constant focal position, said third lens component being composed of only one negative lens element, wherein the following conditions are satisfied: where f 1 : the focal length of the first lens component; f 2 : the focal length of the second lens component; f L : the focal length of the overall system for the narrow-angle position; and m 3 : the lateral magnification of the third lens component.

Claim 3

A compact wide-angle zoom lens according to claim 1 wherein the first lens component is composed of three units each consisting of a single lens element and which are comprised, in order from the object side, of two negative meniscus lenses having a concave surface with a smaller radius of curvature on the image side, and a positive meniscus lens having a convex surface with a smaller radius of curvature on the object side, and the following condition is satisfied: 1.7<Nn (4) where Nn: the average of refractive indices at d-line of the negative lenses in the first lens component.

Claim 4

A compact wide-angle zoom lens according to claim 1 wherein the first lens component is composed of two units each consisting of a single lens element and which are comprised in order from the object side of one negative lens having a concave surface with a smaller radius of curvature on the image side, and one positive meniscus lens having a convex surface with a smaller radius of curvature on the object side, and said first lens component having at least one aspherical surface.

Claim 5

A compact wide-angle zoom lens according to any one of claims 1 to 3 wherein the second lens component is composed of four units each consisting of a single lens element and which are comprised, in order from the object side, of two positive lenses having a convex surface with a smaller radius of curvature on the object side, a negative lens having a concave surface with a smaller radius of curvature on the image side, and a positive lens having a convex surface with a smaller radius of curvature on the image side, and the following condition is satisfied: 1.65<Np (5) where Np: the average of refractive indice at d-line of the positive lens units on the object side in the second lens component.

Claim 6

A compact wide-angle zoom lens according to claim 1, further satisfying the following chart: ______________________________________ 1: 3.5-4.5 f = 36.0-68.0 ω = 32.3°-17.3° Surface No. r d N ν ______________________________________ 1 115.870 1.650 1.83400 37.2 2 26.538 2.202 3 39.330 1.530 1.77250 49.6 4 26.570 2.752 5 26.597 4.463 1.80518 25.4 6 56.948 35.042˜1.50 7 30.766 3.035 1.71300 53.8 8 -118.528 2.700 9 20.453 2.839 1.72000 43.7 10 181.433 0.534 11 -92.385 4.194 1.80518 25.4 12 16.051 5.49 13 -55.592 2.044 1.68893 31.1 14 -23.455 2.28˜19.266 15 -500.003 1.50 1.51633 64.1 16 500.003 f.sub.B = 37.80 ##STR7## ##STR8## m.sub.3 = 1.08 .sup.--Nn = 1.803 .sup.--Np = 1.716 ______________________________________ where f stands for the focal length, ω is the half viewing angle, r is the radius of curvature of each of the surface of a lens, d is the thickness of a lens or the aerial distance between lenses, N is the refractive index of a lens, ν is the Abbe number of a lens, and f B is the back-focus.

Claim 7

A compact wide-angle zoom lens according to claim 1, further satisfying the following chart: ______________________________________ 1: 3.5-4.5 f = 36.0-68.0 ω = 32.3°-17.4° Surface No. r d N ν ______________________________________ 1 115.942 1.650 1.83400 37.2 2 26.340 2.261 3 39.481 1.530 1.77250 49.6 4 26.884 2.671 5 26.676 4.463 1.80518 25.4 6 57.470 35.015˜1.50 7 30.281 3.053 1.71300 53.8 8 -119.377 2.700 9 20.158 2.824 1.72000 43.7 10 151.434 0.540 11 -99.509 4.058 1.80518 25.4 12 15.833 5.591 13 -55.774 2.041 1.68893 31.1 14 -23.736 2.272˜19.317 15 -100.000 1.50 1.58913 61.0 16 -144.907 f.sub.B = 37.80 ##STR9## ##STR10## m.sub.3 = 1.074 .sup.--Nn = 1.803 Np = 1.716. ______________________________________

Claim 8

A compact wide-angle zoom lens according to claim 1, further satisfying the following chart: ______________________________________ 1: 3.5- 4.5 f = 36.0-68.0 ω = 32.3°-17.3° Surface No. r d N ν ______________________________________ 1 118.281 1.650 1.83400 37.2 2 26.270 2.194 3 38.570 1.530 1.71300 53.8 4 26.854 2.828 5 26.721 4.358 1.80518 25.4 6 54.812 35.016˜1.50 7 30.936 3.025 1.71300 53.8 8 -119.565 2.700 9 20.325 2.822 1.72000 43.7 10 154.724 0.533 11 -101.896 4.157 1.80518 25.4 12 16.057 5.458 13 -56.447 2.006 1.68893 31.1 14 -24.281 1.556 15 74.503 1.500 1.51633 64.1 16 60.914 f.sub.B = 38.212 ##STR11## ##STR12## m.sub.3 = 1.05 .sup.--Nn = 1.773 .sup.--Np = 1.716. ______________________________________

Claim 9

A compact wide-angle zoom lens according to claim 1, further satisfying the following chart: ______________________________________ 1:3.5- 4.5 f = 36.15-68.0 ω = 32.2°-17.4° Surface No. r d N ν ______________________________________ 1 274.724 1.800 1.83400 37.2 2 21.981 3.790 3 28.667 5.792 1.80518 25.4 4 80.387 37.795˜ 1.10 5 29.105 3.494 1.73400 51.5 6 -693.812 2.000 7 18.841 3.918 1.67003 47.3 8 72.423 0.702 9 -428.538 3.473 1.80518 25.4 10 15.163 5.559 11 153.119 2.558 1.59270 35.3 12 -36.480 1.00˜ 16.815 13 -1776.573 2.000 1.51633 64.1 14 236.157 f.sub.B = 38.00 Aspherical third surface K = -0.34763 a.sub.1 = 0.13675 × 10.sup.-5 a.sub.2 = -0.13077 × 10.sup.-8 ______________________________________ where the aspherical surface function, X is given by: ##EQU5##