Compact zoom lens system

Claim 2

In a compact zoom lens system which comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, the improvement wherein said first lens unit comprises a positive, a negative and a positive lens element, said second lens unit comprising two cemented negative lenses, each of which comprises a negative lens element on the object side cemented to a positive lens element, and said third lens unit comprising a front sub-unit comprising a positive lens element and a cemented positive lens comprising a positive lens element on the object side cemented to a negative lens element, an intermediate sub-unit consisting solely of a positive lens element and a rear sub-unit consisting solely of a cemented negative meniscus lens comprising a negative lens elements on the object side cemented to a positive lens element and which has a convex surface on the image side, said lens system further satisfying the following conditions: ##EQU2## where f s : focal length of the overall system at the wide-angle end f I : focal length of the first lens unit f II : focal length of the second lens unit f III : focal length of the third lens unit ν i : Abbe number of the ith lens element counted from the object side n i : refractive index at the d line of an ith lens element counted from the object side r j : radius of curvature of a jth lens element counted from the object side f III1 : focal length of the front sub-unit in the third lens unit f III2 : focal length of the intermediate sub-unit in the third lens unit d j : distance between a jth surface and a (j+1) surface as counted from the object side.

Claim 3

The lens system according to claim 1, further satisfying the following conditions: ______________________________________ F.sub.NO = 1:3.9- 4.7- 5.7 f = 72.30- 135.00- 203.49 ω = 17.1- 8.9- 5.9 f.sub.B = 39.88- 51.88- 68.36 Surface No. r.sub.j d.sub.j n.sub.i ν.sub.i ______________________________________ 1 80.080 4.59 1.48749 70.2 2 1080.030 0.10 3 85.000 2.20 1.80518 25.4 4 53.500 0.15 5 55.555 6.03 1.49700 81.6 6 -533.185 2.00- 20.86- 26.67 7 -146.228 1.28 1.77250 49.6 8 38.421 2.11 1.80518 25.4 9 68.597 2.56 10 -50.310 1.28 1.74320 49.3 11 32.535 3.86 1.80518 25.4 12 267.123 21.39- 8.92- 0.69 13 132.321 3.60 1.74320 49.3 14 -62.800 0.10 15 31.787 7.76 1.48749 70.2 16 -35.190 1.29 1.80518 25.4 17 152.991 17.05 18 128.547 3.71 1.64769 33.8 19 -47.616 17.29 20 -23.000 1.20 1.78590 44.2 21 296.503 3.00 1.59270 35.3 22 -60.960 ______________________________________ (1) f.sub.I /f.sub.S = 1.394 (2) | f.sub.II |/f.sub. S = 0.417 (3) f.sub.III /f.sub.s = 0.459 (4) (ν.sub.1 - ν.sub.3)/2 = 75.9, ν.sub.2 = 25.4 (5) (n.sub.4 + n.sub.5 + n.sub.6 + n.sub.7)/4 = 1.782 (6) r.sub.8 = 0.531 f.sub.S r.sub.11 = 0.450 f.sub.S (7) f.sub.III /f.sub.III1 = 0.692 f.sub.III /f.sub.III2 = 0.613 (8) d.sub.17 = 0.236 f.sub.S d.sub.19 = 0.239 f.sub.S Σd + f.sub.B = 142.43 ______________________________________

Claim 4

The lens system according to claim 1, further satisfying the following conditions: ______________________________________ F.sub.NO = 1:3.9- 4.6- 5.7 f = 72.30- 135.00- 203.49 ω = 17.1- 8.9- 6.0 f.sub.B = 39.83- 52.66- 69.37 Surface No. r.sub.j d.sub.j n.sub.i ν.sub.i ______________________________________ 1 79.747 4.68 1.51633 64.1 2 2653.075 0.10 3 86.590 2.20 1.80518 25.4 4 52.481 0.15 5 54.250 5.92 1.49700 81.6 6 -834.174 2.20- 19.98- 25.73 7 -152.136 1.28 1.69680 55.5 8 30.736 2.42 1.76182 26.6 9 58.137 2.73 10 -50.300 1.28 1.74400 44.7 11 32.541 3.82 1.80518 25.4 12 249.746 22.86- 9.53- 0.74 13 139.013 3.60 1.71700 47.9 14 -61.471 0.10 15 32.471 7.69 1.48749 70.2 16 -35.678 1.28 1.80518 25.4 17 147.367 15.49 18 142.098 6.53 1.64769 33.8 19 -48.220 18.32 20 -23.741 1.20 1.78590 44.2 21 457.998 4.12 1.59270 35.3 22 -54.776 ______________________________________ (1) f.sub.I /f.sub.S = 1.383 (2) |f.sub.II |/f.sub.S = 0.421 (3) f.sub.III /f.sub.S = 0.483 (4) (ν.sub.1 + ν.sub.3)/2 = 72.85, ν.sub.2 = 25.4 (5) (n.sub.4 + n.sub.5 + n.sub.6 + n.sub.7)/4 = 1.752 (6) r.sub.8 = 0.425 f.sub.S r.sub.11 = 0.450 f.sub.S (7) f.sub.III /f.sub.III1 = 0.691 f.sub.III /f.sub.III2 = 0.620 (8) d.sub.17 = 0.214 f.sub.S d.sub.19 = 0.253 f.sub.S Σd + f.sub.B = 147.8 ______________________________________

Claim 5

The lens system according to claim 1, further satisfying the following conditions: ______________________________________ F.sub.NO = 1:3.8- 4.6- 5.7 f = 72.27- 135.00- 203.50 ω = 17.0- 8.9- 5.9 f.sub.B = 38.49- 51.51- 67.56 Surface No. r.sub.j d.sub.j n.sub.i ν.sub.i ______________________________________ 1 76.639 6.03 1.48749 70.2 2 -294.907 0.10 3 61.864 2.35 1.80518 25.4 4 42.900 0.16 5 44.250 4.79 1.49700 81.6 6 110.000 2.45- 20.98- 27.29 7 -245.000 1.28 1.77250 49.6 8 33.299 2.30 1.72151 29.2 9 64.350 2.73 10 -42.900 1.28 1.77250 49.6 11 37.714 3.78 1.80518 25.4 12 -859.147 21.28- 8.85- 0.70 13 152.240 3.52 1.74320 49.3 14 -60.691 0.10 15 35.349 7.60 1.48749 70.2 16 -32.725 1.29 1.80518 25.4 17 378.000 16.64 18 199.140 3.72 1.62004 36.3 19 -43.709 18.80 20 -23.205 1.28 1.77250 49.6 21 2539.340 2.55 1.59270 35.3 22 -59.550 ______________________________________ (1) f.sub.I /f.sub.S = 1.468 (2) |f.sub. II |/f.sub.S = 0.420 (3) f.sub.III /f.sub.S = 0.460 (4) (ν.sub.1 + ν.sub.3 )/2 = 72.85, ν.sub.2 = 25.4 (5) (n.sub.4 + n.sub.5 + n.sub.6 + n.sub.7)/4 = 1.768 (6) r.sub.8 = 0.461 f.sub.S r.sub.11 = 0.522 f.sub.S (7) f.sub.III /f.sub.IIIl = 0.692 f.sub.III /f.sub.III2 = 0.571 (8) d.sub.17 = 0.230 f.sub.S d.sub.19 = 0.260 f.sub.S Σd + f.sub.B = 142.52 ______________________________________

Claim 6

The lens system according to claim 1, further satisfying the following conditions: ______________________________________ F.sub.NO = 1:3.8- 4.6- 5.7 f = 72.30- 135.01- 203.55 ω = 17.0- 8.9- 5.9 f.sub.B = 39.62- 53.92- 71.27 Surface No. r.sub.j d.sub.j n.sub.i ν.sub.i ______________________________________ 1 78.946 5.94 1.48749 70.2 2 -271.287 0.10 3 65.758 2.40 1.80518 25.4 4 44.808 0.13 5 45.866 5.30 1.49700 81.6 6 125.800 2.39- 19.61- 25.48 7 -203.165 1.30 1.77250 49.6 8 35.725 2.36 1.72151 29.2 9 69.055 2.74 10 -43.578 1.30 1.77250 49.6 11 35.563 4.00 1.80518 25.4 12 -1963.060 21.02- 8.49- 0.55 13 198.858 3.69 1.74320 49.3 14 -54.471 0.10 15 30.215 7.80 1.48749 70.2 16 -38.083 1.30 1.80518 25.4 17 140.638 20.34 18 84.328 3.66 1.59551 39.2 19 -45.245 13.30 20 -23.436 1.20 1.77250 49.6 21 147.360 2.50 1.59270 35.3 22 -84.362 ______________________________________ (1) f.sub.I /f.sub.S = 1.451 (2) |f.sub.II | /f.sub.S = 0.419 (3) f.sub.III /f.sub.S = 0.462 (4) (ν.sub.1 + ν.sub.3)/2 = 75.9, ν.sub.2 = 25.4 (5) (n.sub.4 + n.sub.5 + n.sub.6 + n.sub.7)/4 = 1.768 (6) r.sub.8 = 0.494 f.sub.S r.sub.11 = 0.492 f.sub.S (7) f.sub.III /f.sub.III1 = 0.730 f.sub.III /f.sub.III2 = 0.668 (8) d.sub.17 = 0.281 f.sub.S d.sub.19 = 0.184 f.sub.S Σd + f.sub.B = 142.49 ______________________________________