Symmetrical lens system affording variable magnification

Claim 2

A varifocal lens system comprising a diaphragm, a pair of movable lens groups located so as to be axially symmetrical with respect to the diaphragm and a pair of stationary lens groups located between said movable lens groups and also symmetrical with respect to the diaphragm, and simultaneously the entire lens system being displaced as a unit in a subordinate relationship relative to the movement of the movable lens groups to satisfy the correct image-forming conditions throughout the entire magnification range while maintaining an object plane and an image plane stationary at a fixed axial distance and wherein said stationary lens groups are positive and said movable lens groups are negative, and the distances between the positive lens groups and the negative lens groups are varied symmetrically with respect to the diaphragm simultaneous with the movement of the entire lens system, wherein each of said lens groups have nearly equivalent absolute values of power and are composed of three lens members, said central lens member in each group being negative and said outer lens members in each group being positive.

Claim 3

A system as in claim 1, wherein said negative lens group includes a positive meniscus lens member whose convex surface faces outwardly and a biconcave lens member and a plano-convex lens member arranged in sequence from the outside towards said diaphragm, said positive lens group including one negative lens member interposed between two positive lens members.

Claim 4

A varifocal lens system of the symmetrical type for affording variable magnification between an object and a sensitive body stationary relative to each other with a predetermined distance therebetween, comprising a diaphragm, a pair of movable lens groups located to be axially symmetrical with respect to the diaphragm and a pair of stationary lens groups located between said movable lens groups and also symmetrical with respect to the diaphragm, said stationary lens groups being positive, said movable lens groups being negative, said movable lens groups being moved axially in symmetrically spaced relationship relative to the diaphragm, and simultaneously the entire system being displaced as a unit in subordinate relationship relative to the movement of the movable lens groups to satisfy the correct image-forming conditions throughout the entire magnification range and affording variable magnification by movement of the entire lens system along the optical axis between the object and a sensitive body and wherein each of said lens groups have nearly equivalent absolute values of power and are composed of three lens members, said central lens member in each group being negative and said outer lens members in each group being positive.

Claim 5

A varifocal lens system of the symmetrical type for affording variable magnification between an object and a sensitive body stationary relative to each other with a predetermined distance therebetween, comprising a diaphragm, a pair of movable lens groups located to be axially symmetrical with respect to the diaphragm and a pair of stationary lens groups located between said movable lens groups and also symmetrical with respect to the diaphragm, said stationary lens groups being positive, said movable lens groups being negative, said movable lens groups being moved axially in symmetrically spaced relationship relative to the diaphragm, and simultaneously the entire system being displaced as a unit in subordinate relationship relative to the movement of the movable lens groups to satisfy the correct image-forming conditions throughout the entire magnification range and affording variable magnification by movement of the entire lens system along the optical axis between the object and a sensitive body and wherein each of said lens groups have nearly equivalent absolute values of power and are composed of three lens members, said central lens member in each group being negative and said outer lens members in each group being positive.

Claim 6

A system as in claim 3, wherein said negative lens group includes a positive meniscus lens member whose convex surface faces outwardly and biconcave lens member and a plano-convex lens member arranged in sequence from the outside towards said diaphragm, said positive lens group including one negative lens member interposed between two positive lens members.

Claim 7

A varifocal lens system comprising a diaphragm, a pair of movable lens groups located to be axially symmetrical with respect to the diaphragm and a pair of stationary lens groups located between said movable lens groups and also symmetrical with respect to the diaphragm, said movable lens groups being moved axially in symmetrically spaced relationship relative to the diaphragm, and simultaneously the entire lens system being displaced as a unit in a subordinate relationship relative to the movement of the movable lens groups to satisfy the correct image-forming conditions throughout the entire magnification range while maintaining an object plane and an image plane stationary at a fixed axial distance, and wherein said four lens groups are identified as I, II, III, and IV and each group includes three lens elements and all the resulting 12 elements constitute the entire lens system, in which I and IV denote symmetrical movable lens group, and II and III denote symmetrical stationary lens groups and in which R: the radii of curvature of the successive lens refracting surfaces D: the axial thicknesses or axial airspaces of the successive lens elements N: the refractive indices (for d line) of the successive lens element glasses V: the Abbe numbers of the successive lens element glasses; __________________________________________________________________________ R.sub.1 = -R.sub.24 = 43.18161 D.sub.1 = D.sub.24 = 1.99514 N.sub.1 = N.sub.12 = 1.62360 V.sub.1 =V.sub.12 =46.9 R.sub.2 = -R.sub.23 = 70.30859 Movable D.sub.2 = D.sub.23 = 5.45201 R.sub.3 = -R.sub.22 = -55.64474 Lens D.sub.3 = D.sub.22 = 0.946 N.sub.2 = N.sub.11 = 1.55957 V.sub.2 =V.sub.11 =61.2 R4 = -R.sub.21 = 33.95923 Group D.sub.4 = D.sub.21 = 1.23186 R.sub.5 = -R.sub.20 = 36.53544 D.sub.5 = D.sub.20 = 3.45097 N.sub.3 = N.sub.10 = 1.53269 V.sub.3 =V.sub.10 =45.9 R.sub.6 = -R.sub.19 = 167.11292 D.sub.6 = D.sub.19 = ∫ (variable) R.sub.7 = -R.sub.18 = -538.71386 Stationary D.sub.7 = D.sub.18 = 2.46077 N.sub.4 = N.sub.9 = 1.69346 V.sub.4 =V.sub.9 =53.3 Lens R.sub.8 = -R.sub.17 = -46.78787 Group D.sub.8 = D.sub.17 = 0.02358 R.sub.9 = -R.sub.16 = -895.93699 D.sub.9 = D.sub.16 = 0.72497 N.sub.5 = N.sub.8 = 1.66691 V.sub.5 =V.sub.8 =33.0 R.sub.10 = -R.sub.15 = 52.68860 Stationary D.sub.10 = D.sub.15 = 0.85464 Lens R.sub.11 = -R.sub.14 = 60.71876 Group D.sub.11 = D.sub.14 = 1.71222 N.sub.6 = N.sub.7 = 1.66986 V.sub.6 =V.sub.7 =57.4 R.sub.12 = - R.sub.13 = ∞ D.sub.12 = D.sub.13 = 1.89119. __________________________________________________________________________

Claim 8

A varifocal lens system comprising a diaphragm, a pair of movable lens groups located to be axially symmetrical with respect to the diaphragm and a pair of stationary lens groups located between said movable lens groups and also symmetrical with respect to the diaphragm, said movable lens groups being moved axially in symmetrically spaced relationship relative to the diaphragm, and simultaneously the entire lens system being displaced as a unit in a subordinate relationship relative to the movement of the movable lens groups to satisfy the correct image-forming conditions throughout the entire magnification range while maintaining an object plane and an image plane stationary at a fixed axial distance, and wherein said four lens groups are identified as I, II, III, and IV and each group includes three lens elements and all the resulting 12 elements constitute the entire lens system, in which I and IV denote symmetrical movable lens group, and II and III denote symmetrical stationary lens groups and in which R: the radii of curvature of the successive lens refracting surfaces D: the axial thicknesses or axial airspaces of the successive lens elements N: the refractive indices (for d line) of the successive lens element glasses V: the Abbe numbers of the successive lens element glasses; __________________________________________________________________________ R.sub.1 = -R.sub.24 = 43.18161 D.sub.1 = D.sub.24 = 1.99514 N.sub.1 = N.sub.12 = 1.62360 V.sub.1 =V.sub.12 =46.9 R.sub.2 = -R.sub.23 = 70.30859 Movable D.sub.2 = D.sub.23 = 5.45201 R.sub.3 = -R.sub.22 = -55.64474 Lens D.sub.3 = D.sub.22 = 0.946 N.sub.2 = N.sub.11 = 1.55957 V.sub.2 =V.sub.11 =61.2 R4 = -R.sub.21 = 33.95923 Group D.sub.4 = D.sub.21 = 1.23186 R.sub.5 = -R.sub.20 = 36.53544 D.sub.5 = D.sub.20 = 3.45097 N.sub.3 = N.sub.10 = 1.53269 V.sub.3 =V.sub.10 =45.9 R.sub.6 = -R.sub.19 = 167.11292 D.sub.6 = D.sub.19 = ∫ (variable) R.sub.7 = -R.sub.18 = -538.71386 Stationary D.sub.7 = D.sub.18 = 2.46077 N.sub.4 = N.sub.9 = 1.69346 V.sub.4 =V.sub.9 =53.3 Lens R.sub.8 = -R.sub.17 = -46.78787 Group D.sub.8 = D.sub.17 = 0.02358 R.sub.9 = -R.sub.16 = -895.93699 D.sub.9 = D.sub.16 = 0.72497 N.sub.5 = N.sub.8 = 1.66691 V.sub.5 =V.sub.8 =33.0 R.sub.10 = -R.sub.15 = 52.68860 Stationary D.sub.10 = D.sub.15 = 0.85464 Lens R.sub.11 = -R.sub.14 = 60.71876 Group D.sub.11 = D.sub.14 = 1.71222 N.sub.6 = N.sub.7 = 1.66986 V.sub.6 =V.sub.7 =57.4 R.sub.12 = - R.sub.13 = ∞ D.sub.12 = D.sub.13 = 1.89119. __________________________________________________________________________