Zoom lens

Claim 2

A zoom lens comprising, from an image side to a subject side, a first lens group having a negative overall power and a second lens group having a positive overall power, the first and second lens groups being movable relative to each other in opposite directions so as to increasingly and decreasingly change an optical distance between said first and second lens groups, thereby varying an overall focal length of the zoom lens, said zoom lens satisfying the following conditions: 2.5<bf.sub.w /f.sub.w ; and 0.68<|f.sub.1 |/f.sub.2 <0.98, where f 1 is a focal length of the first lens group, f 2 is a focal length of the second lens group, f w is a total focal length of the zoom lens at a wide-angle end, and bf w is an axial distance from a rearmost surface of the second lens group to a conjugate point of the second lens group on the subject side with respect to the zoom lens and wherein said second lens group includes at least two concave lens components, a first one of said two concave lens components from the subject side satisfying the following condition: 0.2<f.sub.c /f.sub.2 <0.33; where f c is the focal length of said first one of said two concave lens components.

Claim 3

A zoom lens as defined in claim 1 and scaled to an equivalent focal length of 131.44 mm to a shortest focal length of 83.72 mm substantially as described: ______________________________________ Radius of Axial Distance Curvature Between Surfaces Component (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 89.316 L1 d1 = 3.00 1.800 47.9 R2 = 48.437 d2 = 10.10 R3 = 192.132 L2 d3 = 3.00 1.800 47.9 R4 = 75.376 d4 = 8.56 R5 = -287.895 L3 d5 = 3.00 1.799 47.9 R6 = 225.146 d6 = 2.66 R7 = 82.196 L4 d7 = 11.17 1.618 36.1 R8 = -175.889 d8 (Variable) R9 = 103.111 L5 d9 = 13.48 1.500 54.9 R10 = -84.622 d10 = 6.25 R11 = -51.016 L6 d11 = 9.00 1.641 59.4 R12 = 56.948 L7 d12 = 22.23 1.642 59.4 R13 = -54.657 d13 = 0.20 R14 = -64.669 L8 d14 = 9.00 1.799 25.0 R15 = 264.366 d15 = 3.66 R16 = -321.759 L9 d16 = 7.42 1.571 62.2 R17 = -77.232 d17 = 0.20 R18 = -3050.969 L10 d18 = 7.66 1.657 58.6 R19 = -102.696 ______________________________________ Variable Air Spacing & Focal Length Wide-Angle End Middle-angle Tele-Photo End ______________________________________ d8 (mm) 122.85 87.48 44.65 f (mm) 83.72 99.62 131.65 ______________________________________ where the zoom lens comprises lens components L 1 to L 10 having surfaces R 1 to R 19 , the index of refraction is given by N d for D spectrum, the dispersion is measured by the Abbe Number as given by V d for D spectrum, and axial distances are given by d1 to d18 in millimeters (mm).

Claim 4

A zoom lens as defined in claim 1 and scaled to an equivalent focal length of 83.72 mm to 131.44 mm substantially as described: ______________________________________ Radius of Axial Distance Curvature Between Surfaces Component (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 82.569 L11 d1 = 3.00 1.799 48.0 R2 = 50.417 d2 = 9.37 R3 = 162.329 L12 d3 = 3.00 1.799 48.0 R4 = 70.753 d4 = 8.44 R5 = -599.478 L13 d5 = 7.94 1.754 27.2 R6 = -75.467 d6 = 0.20 R7 = -78.680 L14 d7 = 3.00 1.799 48.0 R8 = 134.780 d8 = 4.86 R9 = 78.706 L15 d9 = 11.45 1.500 54.9 R10 = -160.663 d10 (Variable) R11 = 129.663 L16 d11 = 5.34 1.500 54.9 R12 = -201.838 d12 = 32.72 R13 = -53.377 L17 d13 = 9.01 1.790 47.6 R14 = 45.674 L18 d14 = 14.99 1.800 48.0 R15 = 100.006 d15 = 8.56 R16 = 0.000 L19 d16 = 3.00 1.847 23.9 R17 = 181.942 d17 = 2.30 R18 = 692.519 L20 d18 = 8.72 1.500 65.0 R19 = -86.764 d19 = 0.20 R20 = -1864.120 L21 d20 = 8.15 1.499 65.0 R21 = -103.909 ______________________________________ Variable Air Spacing & Focal Length Wide-Angle End Middle-Angle Tele-Photo End ______________________________________ d10 (mm) 96.51 65.60 27.93 f (mm) 83.64 99.53 131.31 ______________________________________ where the zoom lens comprises lens components L 11 to L 21 having surfaces R 1 to R 21 , the index of refraction is given by N d for D spectrum, the dispersion is measured by the Abbe Number as given by V d for D spectrum, and axial distances are given by d1 to d20 in millimeters (mm).

Claim 5

A zoom lens as defined in claim 1 and scaled to an equivalent focal length of 83.72 mm to 131.44 mm substantially as described: ______________________________________ Radius of Axial Distance Curvature Between Surfaces Component (mm) (mm) N.sub.d V.sub.d ______________________________________ R1 = 99.594 L31 d1 = 3.00 1.799 48.0 R2 = 45.838 d2 = 14.19 R3 = -1297.200 L32 d3 = 3.00 1.799 48.0 R4 = 97.167 d4 = 7.73 R5 = 74.601 L33 d5 = 16.70 1.549 45.7 R6 = -95.185 d6 = 48.08 R7 = -138.791 L34 d7 = 3.00 1.800 48.0 R8 = 87.935 d8 = 1.66 R9 = 86.233 L35 d9 = 3.12 1.800 24.9 R10 = 300.249 d10 (Variable) R11 = 99.309 L36 d11 = 17.75 1.500 54.9 R12 = -45.768 L37 d12 = 9.01 1.730 54.9 R13 = 56.327 L38 d13 = 25.51 1.799 35.3 R14 = -55.211 L39 d14 = 9.00 1.847 23.9 R15 = 165.069 d15 = 2.23 R16 = 386.379 L40 d16 = 11.00 1.708 56.0 R17 = -102.362 d17 = 0.20 R18 = 1111.000 L41 d18 = 10.00 1.799 47.9 R19 = -156.019 ______________________________________ Variable Air Spacing & Focal Length Wide-Angle End Middle-Angle Tele-Photo End ______________________________________ d10 (mm) 36.41 22.80 5.83 f (mm) 83.70 99.60 131.40 ______________________________________ where the zoom lens comprises lens components L 31 to L 41 having surfaces R 1 to R 19 , the index of refraction is given by N d for D spectrum, the dispersion is measured by the Abbe Number as given by V d for D spectrum, and axial distances are given by d1 to d18 in millimeters (mm).