Telephoto lens system

Claim 2

A telephoto lens system comprising from the object side to the image side; a first lens unit of a positive refractive power consisting of a first positive component, a second positive meniscus component convex to the object side, and a third negative component of a doublet composed by cementing together a positive meniscus lens convex to the object side and a negative meniscus lens convex to the object side, the cemented surface in the third component being convex to the object side; a second lens unit of a negative refractive power consisting of a doublet composed by cementing together a positive lens and a negative lens; a third lens unit of a positive refractive power including at least a positive component; and the second lens unit being shiftable along the optical axis with the first and third lens unit being stationary for focusing the whole lens system.

Claim 3

A telephoto lens system as claimed in claim 1, wherein the lens system fulfills the following conditions: 0.4<l.sub.1 /l.sub.2 <1.5 0.15<D/Σd<0.4 wherein: l 1 represents the axial distance between the first and second lens units in the infinity focusing condition; l 2 represents the axial distance between the second and third lens units in the infinity focusing condition; D represents the axial distance between the object side surface of the first component and the image side surface of the third component; and Σd represents the total axial distance of the whole lens system.

Claim 4

A telephoto lens system as claimed in claim 2, wherein the lens system fulfills the following conditions: 15<(νa-νb)<38 (r.sub.a -d.sub.a)<r.sub.b <f wherein: νa represents the Abbe number of the positive lens in the third component; νb represents the Abbe number of the negative lens in the third component; r a represents the radius of cunvature of the object side surface of the positive lens in the third component; r b represents the radius of curvature of the cemented surface in the third component; d a represents the axial thickness of the positive lens in the third component; and f represents the focal length of the whole lens system in the infinity focusing condition.

Claim 5

A telephoto lens system comprising from the object side to the image side; a first lens unit of a positive refractive power including at least a negative lens component; a second lens unit of a negative refractive power; a third lens unit of a positive refractive power; the second lens unit being shiftable along the optical axis with the first and third lens units being stationary for focusing the whole lens system; and wherein the lens system fulfills the following condition:

Claim 6

A telephoto lens system comprising from the object side to the image side; a first lens unit of a positive refractive power including at least a negative lens component; a second lens unit of a negative refractive power; a third lens unit of a positive refractive power; the second lens unit being shiftable along the optical axis with the first and third lens units being stationary for focusing the whole lens system; and wherein the lens system fulfills the following condition:

Claim 7

5f<f I II <2.1f wherein: f represents the focal length of the whole lens system in the infinity focusing condition; and f I II represents the compound focal length of the first and second lens units in the infinity focusing condition.

Claim 8

5f<f I II <2.1f wherein: f represents the focal length of the whole lens system in the infinity focusing condition; and f I II represents the compound focal length of the first and second lens units in the infinity focusing condition.

Claim 9

A telephoto lens system as claimed in claim 4, wherein the first lens unit consists of, from the object side to the image side, a first positive component, a second positive meniscus component convex to the object side, and a third negative component of a doublet composed by cementing together a positive meniscus lens convex to the object side and a negative meniscus lens convex to the object side, the cemented surface in the third component being convex to the object side, and wherein the second lens unit consists of a doublet composed by cementing together a positive lens and a negative lens, and wherein the third lens unit includes at least a positive component.

Claim 10

A telephoto lens system as claimed in claim 5, wherein the lens system further fulfills the following condition: 0.4<l.sub.1 /l.sub.2 <1.5 0.15<D/Σd<0.4 wherein: l 1 represents the axial distance between the first and second lens units in the infinity focusing condition; l 2 represents the axial distance between the second and third lens units in the infinity focusing condition; D represents the axial distance between the object side surface of the first component and the image side surface of the third component; and Σd represents the total axial distance of the whole lens system.

Claim 11

A telephoto lens system as claimed in claim 6, wherein the lens system further fulfills the following conditions: 15<(νa-νb)<38 (r.sub.a -d.sub.a)<r.sub.b <f wherein: νa represents the Abbe number of the positive lens in the third component; νb represents the Abbe number of the negative lens in the third component; r a represents the radius of curvature of the object side surface of the positive meniscus lens in the third component; r b represents the radius of curvature of the cemented surface of the third component; d a represents the axial thickness of the positive lens in the third component; and f represents the focal length of the whole lens system in the infinity focusing position.

Claim 12

A telephoto lens system as claimed in claim 4, wherein the first lens unit consists of, from the object side to the image side, a first positive component, a second positive component, a third negative component, and a fourth negative meniscus component convex to the object side, and wherein the second lens unit consists of a doublet composed by cementing together a positive lens and a negative lens, and wherein the third lens unit includes at least a positive component.

Claim 13

A telephoto type lens system as claimed in claim 8, wherein the lens system fulfills the following conditions: 0.4<l.sub.1 /l.sub.2 <1.5 0.15<D/Σd<0.4 wherein: l 1 represents the axial distance between the first and second lens units in the infinity focusing condition; and l 2 represents the axial distance between the second and third lens units in the infinity focusing condition; D represents the axial distance between the object side surface of the first component and the image side surface of the fourth component; and Σd represents the total axial distance of the whole lens system.

Claim 14

A telephoto lens system of an internal focusing type comprising the following design parameters: ______________________________________ f = 100 F.sub.no. = 2.8 2W = 18° Radius of Axial Refractive Abbe Curvature Distance Index (Nd) Number (υd) ______________________________________ r.sub.1 81.18 d.sub.1 7.38 Nd 1.6073 υd 59.5 r.sub.2 -10595.16 d.sub.2 0.15 r.sub.3 37.86 d.sub.3 4.81 Nd 1.6073 υd 59.5 I r.sub.4 93.44 d.sub.4 0.15 r.sub.5 20.89 d.sub.5 6.00 Nd 1.6689 υd 45.0 r.sub.6 50.14 d.sub.6 1.55 Nd 1.8052 υd 25.4 r.sub.7 16.48 d.sub.7 * 12.54 r.sub.8 204.27 d.sub.8 1.28 Nd 1.8052 υd 25.4 II r.sub.9 -83.35 d.sub.9 1.03 Nd 1.6779 υd 53.4 r.sub.10 31.35 d.sub.10 * 25.12 III r.sub.11 44.09 d.sub.11 6.08 Nd 1.5111 υd 60.5 r.sub.12 819.02 ______________________________________ The asterisk (*) represents a variable air space which is varied for focusing. When focusing to a magnification β= 1/10, d.sub.7 = 19.23 and d.sub.10 = 18.42

Claim 15

A telephoto lens system of an internal focusing type comprising the following design parameters: ______________________________________ f = 100 F.sub.no. = 2.8 2W = 18° Radius of Axial Refractive Abbe Curvature Distance Index (Nd) Number (υd) ______________________________________ r.sub.1 81.18 d.sub.1 7.38 Nd 1.6073 υd 59.5 r.sub.2 -10595.16 d.sub.2 0.15 r.sub.3 37.86 d.sub.3 4.81 Nd 1.6073 υd 59.5 I r.sub.4 93.44 d.sub.4 0.15 r.sub.5 20.89 d.sub.5 6.00 Nd 1.6689 υd 45.0 r.sub.6 50.14 d.sub.6 1.55 Nd 1.8052 υd 25.4 r.sub.7 16.48 d.sub.7 * 12.54 r.sub.8 204.27 d.sub.8 1.28 Nd 1.8052 υd 25.4 II r.sub.9 -83.35 d.sub.9 1.03 Nd 1.6779 υd 53.4 r.sub.10 31.35 d.sub.10 * 25.12 III r.sub.11 44.09 d.sub.11 6.08 Nd 1.5111 υd 60.5 r.sub.12 819.02 ______________________________________ The asterisk (*) represents a variable air space which is varied for focusing. When focusing to a magnification β= 1/10, d.sub.7 = 19.23 and d.sub.10 = 18.42