Reflex finder

Claim 2

A camera comprising a taking objective centered on an axis and provided with several axially spaced components forming a dispersive front lens group and a collective rear lens group, beam-splitting means between said lens groups for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, said finder objective comprising chromatism-correcting lens means including a biconvex lens of relatively low refractive index and relatively high Abbe number and a negative-meniscus lens of relatively high refractive index and relatively low Abbe number, each radius of curvature of any lens of said finder objective exceeding 0.3 times the focal length of the finder objective, said negative-meniscus lens turning a concave side toward said beam-splitting means.

Claim 3

The camera defined in claim 1 wherein said relatively low refractive index ranges between substantially 1.48 and 1.74, said relatively high refractive index ranges between substantially 1.78 and 1.81, said relatively high Abbe number ranges between substantially 44 and 71, and said relatively low Abbe number ranges between substantially 25 and 26.

Claim 4

The camera defined in claim 1 wherein said inverting lens means comprises three air-spaced positive lens members.

Claim 5

The camera defined in claim 3 wherein said three positive lens members include a positive-meniscus lens proximal to said finder objective.

Claim 6

The camera defined in claim 1 wherein said biconvex lens and said negative-meniscus lens are singlets air-spaced from each other.

Claim 7

The camera defined in claim 5 wherein said biconvex lens lies proximal to said beam-splitting means.

Claim 8

The camera defined in claim 1 wherein said biconvex lens and said negative-meniscus lens are cemented to each other to form a doublet.

Claim 9

The camera defined in claim 7 wherein said finder objective further comprises a positive front lens between said beam-splitting means and said doublet.

Claim 10

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens of relatively high Abbe number and a negative-meniscus lens of relatively low Abbe number, each radius of curvature of any lens of said finder objective exceeding 0.3 times the focal length of the finder objective, said negative-meniscus lens turning a concave side toward said beam-splitting means; said eyepiece consisting of four air-spaced lens members, i.e. a biconcave singlet L C1 , two biconvex singlets L C2 , L C3 and a planoconvex singlet L C4 , said lens members L C1 - L C4 having radii of curvature r C1 - r C8 , thicknesses d C1 - d C4 , separations l C1 - l C3 , refractive indices n d and Abbe numbers v d substantially as listed in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.C1 = -19.78 L.sub.C1 d.sub.C1 = 1.2 / 1.755 / 27.6 r.sub.C2 = +19.78 l.sub.C1 = 0.5 r.sub.C3 = +24.17 L.sub.C2 d.sub.C2 = 4.5 / 1.658 / 50.9 r.sub.C4 = -13.501 l.sub.C2 = 0.1 r.sub.C5 = +38.521 L.sub.C3 d.sub.C3 = 4.5 / 1.623 / 58.1 r.sub.C6 = -38.521 l.sub.C3 = 0.1 r.sub.C7 = +19.714 L.sub.C4 d.sub.C4 = 3.6 / 1.623 / 58.1 r.sub.C8 = ∞. ______________________________________

Claim 11

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens of relatively high Abbe number and a negative-meniscus lens of relatively low Abbe number, each radius of curvature of any lens of said finder objective exceeding 0.3 times the focal length of the finder objective, said negative-meniscus lens turning a concave side toward said beam-splitting means; said eyepiece consisting of four air-spaced lens members, i.e. a biconcave singlet L C1 , two biconvex singlets L C2 , L C3 and a planoconvex singlet L C4 , said lens members L C1 - L C4 having radii of curvature r C1 - r C8 , thicknesses d C1 - d C4 , separations l C1 - l C3 , refractive indices n d and Abbe numbers v d substantially as listed in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.C1 = -19.78 L.sub.C1 d.sub.C1 = 1.2 / 1.755 / 27.6 r.sub.C2 = +19.78 l.sub.C1 = 0.5 r.sub.C3 = +24.17 L.sub.C2 d.sub.C2 = 4.5 / 1.658 / 50.9 r.sub.C4 = -13.501 l.sub.C2 = 0.1 r.sub.C5 = +38.521 L.sub.C3 d.sub.C3 = 4.5 / 1.623 / 58.1 r.sub.C6 = -38.521 l.sub.C3 = 0.1 r.sub.C7 = +19.714 L.sub.C4 d.sub.C4 = 3.6 / 1.623 / 58.1 r.sub.C8 = ∞. ______________________________________

Claim 12

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = +27.487 L.sub.A1 d.sub.A1 = 2.3 / 1.744 / 44.8 r.sub.A2 = -7.167 l.sub.A1 = 0.13 r.sub.A3 = -6.100 L.sub.A2 d.sub.A2 = 2.4 / 1.805 / 25.4 r.sub.A4 = -9.360. ______________________________________

Claim 13

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = +27.487 L.sub.A1 d.sub.A1 = 2.3 / 1.744 / 44.8 r.sub.A2 = -7.167 l.sub.A1 = 0.13 r.sub.A3 = -6.100 L.sub.A2 d.sub.A2 = 2.4 / 1.805 / 25.4 r.sub.A4 = -9.360. ______________________________________

Claim 14

The improvement defined in claim 10 wherein said biconvex lens lies forwardly of said negative-meniscus lens, said finder objective having a focal length of substantially 12.075.

Claim 15

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = -23.798 L.sub.A1 d.sub.A1 = 2.3 / 1.641 / 60.1 r.sub.A2 = -6.151 l.sub.A1 = 0.15 r.sub.A3 = -5.284 L.sub.A2 d.sub.A2 = 2.0 / 1.805 / 25.4 r.sub.A4 = -7.803. ______________________________________

Claim 16

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = -23.798 L.sub.A1 d.sub.A1 = 2.3 / 1.641 / 60.1 r.sub.A2 = -6.151 l.sub.A1 = 0.15 r.sub.A3 = -5.284 L.sub.A2 d.sub.A2 = 2.0 / 1.805 / 25.4 r.sub.A4 = -7.803. ______________________________________

Claim 17

The improvement defined in claim 12 wherein said biconvex lens lies forwardly of said negative-meniscus lens, said finder objective having a focal length of substantially 12.103.

Claim 18

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = +20.0 L.sub.A1 d.sub.A1 = 2.0 / 1.620 / 60.3 r.sub.A2 = -6.524 l.sub.A1 = 0.4 r.sub.A3 = -5.5 L.sub.A2 d.sub.A2 = 1.0 / 1.785 / 25.8 r.sub.A4 = -8.177. ______________________________________

Claim 19

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a biconvex lens L A1 with radii of curvature r A1 , r A2 and thickness d A1 followed by a negative-meniscus lens L A2 with radii of curvature r A3 , r A4 and thickness d A2 , said negative-meniscus lens L A2 being separated from said biconvex lens L A1 by an air space l A1 ; said radii r A1 - r A4 , thicknesses d A1 , d A2 and air space l A1 , the refractive indices of said lenses L A1 , L A2 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 = +20.0 L.sub.A1 d.sub.A1 = 2.0 / 1.620 / 60.3 r.sub.A2 = -6.524 l.sub.A1 = 0.4 r.sub.A3 = -5.5 L.sub.A2 d.sub.A2 = 1.0 / 1.785 / 25.8 r.sub.A4 = -8.177. ______________________________________

Claim 20

The improvement defined in claim 14 wherein said biconvex lens lies forwardly of said negative-meniscus lens, said finder objective having a focal length of substantially 12.460.

Claim 21

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature r" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +43.586 L.sub.A1 " d.sub.A1 " = 1.7 / 1.658 / 50.9 r.sub.A2 " = -43.586 l.sub.A1 " = 2.8 r.sub.A3 " = +49.735 L.sub.A2 " d.sub.A2 " = 3.4 / 1.658 / 50.9 r.sub.A4 " = -10.020 L.sub.A3 " d.sub.A3 " = 1.2 / 1.805 / 25.4 r.sub.A5 " = -27.179. ______________________________________

Claim 22

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature r" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +43.586 L.sub.A1 " d.sub.A1 " = 1.7 / 1.658 / 50.9 r.sub.A2 " = -43.586 l.sub.A1 " = 2.8 r.sub.A3 " = +49.735 L.sub.A2 " d.sub.A2 " = 3.4 / 1.658 / 50.9 r.sub.A4 " = -10.020 L.sub.A3 " d.sub.A3 " = 1.2 / 1.805 / 25.4 r.sub.A5 " = -27.179. ______________________________________

Claim 23

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature R" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers V d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +27.986 L.sub.A1 " d.sub.A1 " = 2.0 / 1.724 / 38.1 r.sub.A2 " = +150.000 l.sub.A1 " = 2.0 r.sub.A3 " = +17.000 L.sub.A2 " d.sub.A2 " = 3.7 / 1.487 / 70.4 r.sub.A4 " = -10.620 L.sub.A3 " d.sub.A3 " = 1.3 / 1.805 / 25.4 r.sub.A5 " = -72.382. ______________________________________

Claim 24

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature R" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers V d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +27.986 L.sub.A1 " d.sub.A1 " = 2.0 / 1.724 / 38.1 r.sub.A2 " = +150.000 l.sub.A1 " = 2.0 r.sub.A3 " = +17.000 L.sub.A2 " d.sub.A2 " = 3.7 / 1.487 / 70.4 r.sub.A4 " = -10.620 L.sub.A3 " d.sub.A3 " = 1.3 / 1.805 / 25.4 r.sub.A5 " = -72.382. ______________________________________

Claim 25

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature R" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +25.250 L.sub.A1 " d.sub.A1 " = 2.0 / 1.623 / 58.1 r.sub.A2 " = ∞ l.sub.A1 " = 3.0 r.sub.A3 " = +19.039 L.sub.A2 " d.sub.A2 " = 4.0 / 1.532 / 48.3 r.sub.A4 " = -10.512 L.sub.A3 " d.sub.A3 " = 1.0 / 1.805 / 25.4 r.sub.A5 " = -614.079. -- ______________________________________

Claim 26

In a camera comprising a taking objective centered on an axis and provided with several axially spaced components, beam-splitting means between two of said components for diverting incident light rays onto an off-axial ray path, and a view finder in said ray path including a finder objective, an eyepiece and inverting lens means therebetween, the improvement wherein said finder objective comprises achromatic lens means including a positive front lens L" A1 with radii of curvature r" A1 , r" A2 and thickness d" A1 followed by a doublet consisting of a biconvex lens L" A2 with radii of curvature R" A3 , r" A4 and thickness d" A2 cemented onto a negative-meniscus lens L" A3 with radii of curvature r" A4 , r" A5 and thickness d" A3 , said positive front lens L" A1 being separated from said doublet L" A2 , L" A3 by an air space l" A1 ; said radii r" A1 - r" A5 , thicknesses d" A1 - d" A3 and air space l" A1 , the refractive indices of said lenses L" A1 - L" A3 and their Abbe numbers v d having numerical values substantially as given in the following table: ______________________________________ n.sub.d v.sub.d ______________________________________ r.sub.A1 " = +25.250 L.sub.A1 " d.sub.A1 " = 2.0 / 1.623 / 58.1 r.sub.A2 " = ∞ l.sub.A1 " = 3.0 r.sub.A3 " = +19.039 L.sub.A2 " d.sub.A2 " = 4.0 / 1.532 / 48.3 r.sub.A4 " = -10.512 L.sub.A3 " d.sub.A3 " = 1.0 / 1.805 / 25.4 r.sub.A5 " = -614.079. -- ______________________________________