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US 6,560,036 B2Granted
Real image type view finder
AssigneeOlympus Optical Co., Ltd.
InventorsToshio Takahashi, Akiyoshi Tochigi
Life of this patent
Estimating the term…
Abstract
A real image type view finder comprising an objective optical system which has positive refractive power and forms an intermediate image, an image erecting optical system which erects the intermediate image and an eyepiece optical system which leads the intermediate image to an observer's eye, in which the objective optical system comprises a first positive lens unit, a second negative lens unit, a third negative lens unit and a fourth positive lens unit, moves the second lens unit and the third lens unit for a magnification change, has a vari-focal ratio on the order of 4, and has favorable optical performance over an entire zooming region.
Claims33
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- and
- an eyepiece optical system which leads said intermediate image to an observer's eye,
- wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (1):
- 0.97<Lr/S<1.2 (1)
- wherein a reference symbol Lr represents an optical path length as measured from a location of the intermediate image to an object side surface of the eyepiece optical system and a reference symbol S designates a distance as measured from a most object side curved surface of the objective optical system to a most image side curved surface of the objective optical system.
4 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- and an eyepiece optical which leads said intermediate image to an observer's eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit in an identical direction along an optical axis and satisfies the following condition (2):
- −0.4<f4/(f3×z)<−0.185 (2)
- wherein reference symbols f3 and f4 represent focal lengths of the third lens unit and the fourth lens unit respectively, and a reference symbol z designates a vari-focal ratio.
2 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- and an eyepiece optical system which leads said intermediate image to an observer's eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (6):
- 1.1<(f1×f2)/(f3×f4)<1.6 (6)
- wherein f1, f2, f3 and f4 represent focal lengths of the first lens unit, the second lens unit, the third lens unit and the fourth lens unit respectively.
2 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which erects said intermediate image;
- and an eyepiece optical system which leads said intermediate image to an observer's eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9):
- 0.8<(L3−L2)×z/L2<5.5 (9)
- wherein reference symbols L2 and L3 represent moving distances of the second lens unit and the third lens unit from a wide position to a tele position, and a reference symbol z designates a vari-focal ratio.
2 more elements
A real image type view finder comprising:
- a photographic optical system;
- an objective optical system which is disposed separately from the photographic optical system and forms an intermediate image;
- a visual field frame which is disposed in the vicinity of said intermediate image;
- an image erecting optical system which erects said intermediate image;
- and an eyepiece optical system, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, and satisfies the following condition (7):
- 0.52<H (max)/fe<1 (7)
- wherein a reference symbol H (max) represents a maximum width of the visual field frame and a reference symbol fe designates a focal length of an optical system as a whole which is on an emergence side of the intermediate image.
4 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which erects said intermediate image;
- and
- an eyepiece optical system which leads said intermediate image to an observer's eye, wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9):
- 0.8<(L3−L2)×z/L2<5.5 (9)
- wherein reference symbols L2 and L3 represent moving distances of the second lens unit and the third lens unit from a wide position to a tele position, and a reference symbol z designates a van-focal ratio, and
- wherein the view finder is configured to permit performing diopter adjustment at an assembling stage by changing a location of the second lens unit independently or locations of the second lens unit and the third lens unit integrally of said objective optical system.
4 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has a positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- an eyepiece optical system which leads said intermediate image to an observer's eye;
- and
- an optical member which is disposed in the vicinity of said intermediate image separately from said prism,
- wherein said optical member is exchangeable independently with another optical member for an identical specification, and
- wherein an aperture stop which has variable aperture diameter is disposed in said objective optical system.
4 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which erects said intermediate image;
- and
- an eyepiece optical system which leads said intermediate image to an observer's eye,
- wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9):
- 0.8<(L3−L2)×z/L2<5.5 (9)
- wherein reference symbols L2 and L3 represent moving distances of the second lens unit and the third lens unit from a wide position to a tele position, and a reference symbol z designates a van-focal ration, and
- wherein an aperture stop which has variable aperture diameter is disposed in said objective optical system.
5 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which erects said intermediate image and an eyepiece optical system which leads said intermediate image to an observer's eye,
- wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9):
- 0.8<(L3−L2)×z/L2<5.5 (9)
- wherein reference symbols L2 and L3 represent moving distances of the second lens unit and the third lens unit from a wide position to a tele position, and a reference symbol z designates a van-focal ratio, and wherein each lens unit of said objective optical system consists only of a lens element.
2 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- an eyepiece optical system which leads said intermediate image to an observer's eye;
- and
- an optical member which is disposed in the vicinity of said intermediate image separately from said prism,
- wherein said optical member is exchangeable independently with another optical member for an identical specification, and wherein the objective optical system has a van-focal ratio of 3.5 or higher.
3 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which erects said intermediate image;
- and an eyepiece optical system which leads said intermediate image to an observer's eye,
- wherein said objective optical system comprises, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive refractive power, changes a magnification by moving said second lens unit and said third lens unit, and satisfies the following condition (9):
- 0.8<(L3−L2)×z/L2<5.5 (9)
- wherein reference symbols L2 and L3 represent moving distances of the second lens unit and the third lens unit from a wide position to a tele position, and a reference symbol z designates a van-focal ratio, and wherein the objective optical system has a van-focal ratio of 3.5 or higher.
3 more elements
A real image type view finder comprising:
- an objective optical system which forms an intermediate image and has positive refractive power;
- an image erecting optical system which comprises at least a prism and erects said intermediate image;
- an eyepiece optical system which leads said intermediate image to an observer's eye;
- and
- an optical member which is disposed in the vicinity of said intermediate image separately from said prism, and
- wherein the objective optical system has a van-focal ratio of 3.5 or higher.
3 more elements
Dependencies are inferred from the claim text.