Claims
- 1. An inverse telescopic wide angle lens comprising:
- a diaphragm;
- a front lens group of an integral positive or negative refractive power, positioned in the object side in front of said diaphragm and having a first lens group of a negative refractive power including a negative lens of which an image-side air-contacting surface is formed as an aspherical surface concave to the image side, and a second lens group of a positive refractive power positioned between said first lens group and said diaphragm; and
- a rear lens group of a positive refractive power, positioned at the image side behind said diaphragm,
- wherein said rear lens group includes a movable lens group consisting of plural lenses which are integrally movable for focusing, wherein said front lens group is fixed, and the focusing is conducted by the movement of said movable lens group alone in such a manner as to vary the rear focal length between said movable lens group and the image plane.
- 2. An inverse telescopic wide angle lens according to claim 1, wherein said rear lens group consists solely of the movable lens group integrally movable for focusing, and the focusing is conducted by the movement of said rear lens group alone, in such a manner as to vary the air gap between said front lens group and said movable lens group.
- 3. An inverse telescopic wide angle lens according to claim 1, wherein said rear lens group consists of a fixed lens group and a movable focusing lens group provided across at least an air gap, wherein said front lens group and said fixed lens group are maintained fixed, and the focusing is conducted by the movement of said movable focusing lens group alone in such a manner as to vary said air gap.
- 4. An inverse telescopic wide angle lens according to claim 1, wherein said negative lens in said first lens group is so constructed that the absolute value of the refractive power of said concave surface on the optical axis is larger than that of the refractive power of the surface at the object side on the optical axis, and that the form of said aspherical concave surface of said negative lens at the image side, when represented by an equation:
- x=Cy.sub.2 /{(1+(1-.kappa.C.sup.2 y.sup.2).sup.1/2 }+C.sub.4 y.sup.4 +C.sub.6 y.sup.6 + . . .
- defining the axial distance x from the peak point of a curve constituting said aspherical surface as a function of the distance y of said curve from the optical axis, with a curvature C at said peak point of the curve a conical constant .kappa. and aspherical constants C.sub.4, C.sub.6, . . . , satisfies a condition -5<.kappa.<0.5; and that the effective diameter .phi. of the closest to the object in said first lens group is so constructed as to satisfy a condition .phi.<4.multidot.f.multidot.tan.theta. wherein f is the focal distance of the entire lens system and .theta. is the half image angle.
- 5. An inverse telescopic wide angle lens according to claim 1, wherein said first lens group is so constructed as to further satisfy a condition:
- 0.4<.vertline.f.sub.1 /f.vertline.<2.0
- wherein f is the focal distance of the entire lens system, and f.sub.1 is the focal distance of said first lens group.
- 6. An inverse telescopic wide angle lens according to claim 1, wherein the concave surface, at the image side, of said negative lens in said first lens group is formed as a parabolic face satisfying the following condition:
- x=y.sup.2 /2.multidot.r.sub.2 (.kappa.=0,C.sub.4,C.sub.6, . . . =0)
- defining axial distance x from the peak point of said curved surface as a function of distance y of said curved surface from the optical axis, wherein r.sub.2 is the radius of curvature at said peak point of the curved surface.
- 7. An inverse telescopic wide angle lens according to claim 1, wherein said rear lens group is composed, in the order from the object side, of an adhered first lens consisting of a biconvex positive lens and a negative meniscus lens convex to the image side, an adhered second lens consisting of a positive meniscus lens convex to the image side and a biconcave negative lens having a concave surface of a stronger curvature at the object side, a third positive meniscus lens convex to the image side, and a fourth biconvex lens having a surface of a stronger curvature at the image side; and wherein said front lens group is maintained fixed while said adhered first lens to said fourth lens are rendered integrally movable for focusing in such a manner as to vary the air gap to said front lens group.
- 8. An inverse telescopic wide angle lens according to claim 1, wherein said rear lens group is composed, in the order from the object side, of an adhered first lens consisting of a biconvex positive lens and a negative meniscus lens convex to the image side, an adhered second lens consisting of a positive meniscus lens convex to the image side and a biconcave negative lens having a concave surface of a stronger curvature at the object side, a third positive meniscus lens convex to the image side, and a fourth biconvex lens having a surface of stronger curvature at the image side; and wherein said front lens group and said adhered first lens are maintained fixed while said adhered second lens to said fourth lens are rendered integrally movable for focusing in such a manner as to vary the air gap between said first and second lenses.
- 9. An inverse telescopic wide angle lens according to claim 1, wherein said rear lens group includes, in the order from the object side, an adhered first lens consisting of a biconvex positive lens and a biconcave negative lens, an adhered second lens consisting of a negative meniscus lens convex to the object side and a biconvex positive lens, and a third biconvex lens having a surface of a stronger curvature at the image side, and wherein said front lens group is maintained fixed while said adhered first lens to said third lens are rendered integrally movable for focusing in such a manner as to vary the air gap to said front lens group.
- 10. An inverse telescopic wide angle lens according to claim 1, constructed according to the following data, wherein r.sub.i i is the radius of curvature of an i-th face (i=1, 2, 3, . . .) numbered from the object side, d.sub.i is the axial distance between i-th and (i+1)-th lens faces, n.sub.di is the refractive index, for d-line, of the medium between the i-th and (i+1)-th faces, .nu..sub.di is Abee's number of the medium between the i-th and (i+1)-th faces (Abbe's number for air being left blank), F.sub.NO is the F number, and asterisk (*) indicates an aspherical face, also either of the distances d.sub.7 and d.sub.10, marked with .DELTA., is variable:
- ______________________________________f = 100, F.sub.NO = 2.8, 2.sub..theta. = 110.degree.i r.sub.i d.sub.i n.sub.di .nu..sub.di______________________________________ 1 733.445 5.464 1.77279 49.45*2 96.873 109.289 1.00000 3 226.711 26.719 1.77279 49.45 4 96.883 109.289 1.59507 35.51 5 1255.857 1.639 1.00000 6 123.439 43.715 1.60342 38.03 7 245.521 .DELTA.16.393 1.00000 8 330.203 19.672 1.57501 41.42 9 -61.987 10.928 1.74810 52.3010 -477.301 .DELTA.10.928 1.0000011 -462.429 26.229 1.80411 46.5512 -99.306 5.464 1.80518 25.3513 275.371 10.928 1.0000014 -249.244 14.754 1.62041 60.1415 -104.473 1.092 1.0000016 327.801 19.130 1.62041 60.1417 -210.719 206.010 1.00000 (variable)______________________________________ rear focal length: 206.0 mm when focused to inifinity.
- 11. An inverse telescopic wide angle lens according to claim 1, constructed according to the following data, wherein r.sub.i is the radius of curvature of an i-th face (i=1, 2, 3, . . .) numbered from the object side, d.sub.i is the axial distance between i-th and (i+1)-th lens faces, n.sub.di is the refractive index, for d-line, of the medium between the i-th and (i+1)-th faces. .nu..sub.di is Abbe's number of the medium between the i-th and (i+1)-th faces (Abbe's number for air being left blank), F.sub.NO is the F number, and asterisk (*) indicates an aspherical face:
- ______________________________________f = 100, F.sub.NO = 3.5, 2.sub..theta. = 110.degree.i r.sub.i d.sub.i n.sub.di .nu..sub.di______________________________________ 1 1141.843 9.868 1.77279 49.45*2 94.601 85.526 1.00000 3 590.915 85.449 1.61293 36.98 4 -210.851 71.236 1.71300 59.93 5 -495.018 1.315 1.00000 6 139.541 9.868 1.65160 58.50 7 97.296 23.026 1.00000 8 176.250 39.473 1.62004 36.27 9 -201.482 84.210 1.80411 46.5510 208.521 1.315 1.0000011 131.381 13.157 1.58144 40.7612 -540.218 24.342 1.00000 (variable)13 211.677 19.736 1.51680 64.1014 -96.540 6.578 1.79631 40.9015 242.213 7.894 1.0000016 -3841.914 4.605 1.79504 28.5717 159.372 34.210 1.51680 64.1018 -110.558 1.315 1.0000019 1646.110 23.026 1.51680 64.1020 -172.890 250.995 1.00000 (variable)______________________________________ rear focal length: 251.0 mm when focused to infinity.
- 12. An inverse telescopic wide angle lens according to claim 1, constructed according to the following data, wherein r.sub.i is the radius of curvature of an i-th face (i=1, 2, 3, . . .) numbered from the object side, d.sub.i is the axial distance between i-th and (i+1)-th lens faces, n.sub.di is the refractive index, for d-line, of the medium between the i-th and (i+1)-th faces, .nu..sub.di is Abbe's number of the medium for air being left blank), F.sub.NO is the F number, and asterisk (*) indicates an aspherical face:
- ______________________________________f = 100, F.sub.NO = 3.5, 2.sub..theta. = 110.degree.i r.sub.i d.sub.i n.sub.di .nu..sub.di______________________________________ 1 1333.575 9.868 1.74810 52.30*2 106.710 98.305 1.00000 3 221.380 23.026 1.71300 59.93 4 138.762 106.382 1.59507 35.51 5 923.259 1.315 1.00000 6 192.744 9.868 1.65160 58.50 7 109.801 32.894 1.00000 8 187.842 16.447 1.74810 52.30 9 88.457 132.099 1.62004 36.2710 356.513 1.315 1.0000011 139.600 13.157 1.51680 64.1012 348.181 24.342 1.00000 (variable)13 178.124 19.736 1.51680 64.1014 -108.565 6.578 1.79668 45.3715 311.912 11.184 1.0000016 -2911.027 4.605 1.80384 33.9217 158.548 34.210 1.51680 64.1018 -112.805 1.315 1.0000019 342.313 29.605 1.51680 64.1020 -239.277 258.613 1.00000 (variable)______________________________________ rear focal length: 258.6 mm when focused to infinity.
- 13. An inverse telescopic wide angle lens according to claim 1, constructed according to the following data, wherein r.sub.i is the radius of curvature of an i-th face (i=1, 2, 3, . . .) numbered from the object side, d.sub.i is the axial distance between i-th and (i+1)-th lens faces, n.sub.di is the refractive index, for d-line, of the medium between the i-th and (i+1)-th faces, .nu..sub.di is Abbe's number of the medium between the i-th and (i+1)-th faces (Abbe's number for air being left blank), F.sub.NO is the F number, and asterisk (*) indicates an aspherical face:
- ______________________________________f = 100, F.sub.NO = 2.8, 2.sub..theta. = 110.degree.i r.sub.i d.sub.i n.sub.di .nu..sub.di______________________________________ 1 1319.491 9.868 1.74810 52.30*2 108.017 82.236 1.00000 3 288.869 23.026 1.71300 59.93 4 147.353 108.552 1.59507 35.51 5 -1375.554 1.315 1.00000 6 187.777 9.868 1.65160 58.50 7 99.315 32.894 1.00000 8 212.517 16.447 1.74810 52.30 9 83.032 114.728 1.62004 36.2710 217.920 1.315 1.0000011 146.295 13.157 1.51680 64.1012 -986.512 24.342 1.00000 (variable)13 120.646 19.736 1.51680 64.1014 -411.297 6.578 1.79668 45.3715 150.107 11.184 1.0000016 800.896 4.605 1.80384 33.9217 127.565 34.210 1.51680 64.1018 -136.158 1.315 1.0000019 589.798 29.605 1.51680 64.1020 -220.870 248.442 1.00000 (variable)______________________________________ rear focal length: 248.4 mm when focused to infinity.
Priority Claims (2)
Number |
Date |
Country |
Kind |
3-207704 |
Aug 1991 |
JPX |
|
3-306683 |
Oct 1991 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 093,727 filed Jul. 20, 1993 which is a continuation of application Ser. No. 931,347 filed Aug. 18, 1991, (now abandoned).
US Referenced Citations (3)
Divisions (1)
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Number |
Date |
Country |
Parent |
93727 |
Jul 1993 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
931347 |
Aug 1992 |
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