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Real-image zoom viewfinder and imaging apparatus

a technology of which is applied in the field of real-image zoom viewfinder and imaging apparatus, can solve the problems of difficult to achieve sufficient thickness reduction, difficult to achieve the reduction of thickness while ensuring a zoom ratio of around 4:1, etc., and achieves the reduction of optical path length, shorter optical path length, and longer optical path length

Inactive Publication Date: 2014-04-24
FUJIFILM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a real-image zoom viewfinder that can achieve thickness reduction in the imaging direction without degrading the optical performance. This is achieved by satisfying a conditional expression and reducing the optical path length in the imaging direction without reducing the entire optical path length of light traveling through the viewfinder. The invention also provides an imaging apparatus employing this real-image zoom viewfinder.

Problems solved by technology

The real-image viewfinder disclosed in Patent Document 1, however, has a problem that the thickness reduction while ensuring a zoom ratio of around 4:1 is difficult to be achieved since the length in the thickness direction of a camera is a sum of thicknesses of the objective lens, the prism and the eyepiece lens.
However, it is still difficult to achieve sufficient thickness reduction since a significant thickness is required to dispose two lens groups including the first lens group and the second lens group, which are disposed on the object side of the third lens group for bending the optical path and are arranged in the imaging direction.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0081]FIG. 6 is a diagram illustrating a developed view of the configuration and the optical path of the real-image zoom viewfinder of Example 1.

[0082]Table 1A, which will be described later, shows data about the real-image zoom viewfinder of Example 1. Lens data is shown in the upper table of Table 1A, and data relating to zoom of the real-image zoom viewfinder is shown in the lower table of Table 1A.

[0083]In the lens data shown in the upper table of Table 1A, each value in the column of “Surface number Si” represents the surface number of the i-th (i=1, 2, 3, . . . ) lens surface, or the like, where the number is sequentially increased from the most object-side surface toward the image side.

[0084]Each value in the column of “Radius of curvature Ri” represents the radius of curvature of the i-th (i=1, 2, 3, . . . ) surface. Each value in the column of “Surface interval Di” (i=1, 2, 3, . . . ) represents the surface interval between the i-th surface and the i+1-th surface along the ...

example 2

[0100]FIG. 7 is a diagram illustrating a developed view of the configuration and the optical path of the real-image zoom viewfinder of Example 2.

[0101]Table 2A shows data about the real-image zoom viewfinder of Example 2. Lens data is shown in the upper table of Table 2A, and data relating to zoom of the real-image zoom viewfinder is shown in the lower table of Table 2A.

TABLE 2AExample 2SurfaceRadiusSurfaceAbbenumber Siof curvature Riinterval DiRefractive index Njnumber νj*118.74221.8001.58364130.27*25.29651.4003∞7.6281.84666023.784∞D4532.1362.5001.49023357.45*6−13.8448D6721.34761.7501.48749070.23865.0217D89∞9.0001.49023357.4510∞0.50011∞19.125 1.49023357.4512∞3.3791345.6734.5001.49023357.45*14−10.3661Data relating to zoomSpecificationsWide-angle endTelephoto endFinder magnification: m0.431.72Angle of field: 2ω58.313.3Interval: D425.6482.458Interval: D611.0522.140Interval: D89.95442.056*aspherical surface

[0102]Table 2B shows aspherical coefficients representing the shape of each asph...

example 3

[0106]FIG. 8 is a diagram illustrating a developed view of the configuration and the optical path of the real-image zoom viewfinder of Example 3.

[0107]Table 3A shows data about the real-image zoom viewfinder of Example 3. Lens data is shown in the upper table of Table 3A, and data relating to zoom of the real-image zoom viewfinder is shown in the lower table of Table 3A.

TABLE 3AExample 3SurfaceRadiusSurfaceAbbenumber Siof curvature Riinterval DiRefractive index Njnumber νj*114.7921.8001.58364130.27*24.15671.4003∞7.6281.84666023.784∞D4519.43742.5001.49023357.45*6−12.4582D6714.27341.7501.48749070.23833.1381D89∞9.0001.49023357.4510∞0.50011∞19.125 1.49023357.4512∞2.0001323.00913.0001.49023357.45*14−12.9246Data relating to zoomSpecificationsWide-angle endTelephoto endFinder magnification: m0.301.21Angle of field: 2ω69.617.2Interval: D419.6871.454Interval: D60.5000.667Interval: D89.72027.786*aspherical surface

[0108]Table 3B shows aspherical coefficients representing the shape of each asph...

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Abstract

A zoom viewfinder substantially consists of, in order from the object side: a variable-magnification objective lens system substantially consisting of a first lens group that includes a negative first-group first lens and a reflective member arranged in this order from the object side, a positive second lens group that is moved during magnification change, and a positive third lens group that is moved during magnification change; an erect optical system having a reflective surface for converting an inverted image into an erect image; and a positive eyepiece lens system, wherein conditional expressions (1), (2A) and (3) below are satisfied:1.5<U2 / U1<3.0  (1),1.76≦|f2 / f1|<2.0  (2A) and1.0<f3 / f2<5.0  (3).

Description

TECHNICAL FIELD[0001]The present invention relates to a real-image zoom viewfinder and an imaging apparatus which can provide a good viewfinder image by appropriately setting a variable-magnification objective lens system, an erect optical system and an eyepiece lens system.BACKGROUND ART[0002]Conventionally, real-image zoom viewfinders that are configured to form a vertically and horizontally inverted real image using an objective lens having a positive refractive power, convert the real image into an erect image using an erecting prism that is formed by a combination of one or more prisms, and enlarge the erect image using an eyepiece lens having a positive refractive power are known. Further, imaging apparatuses equipped with such a real-image zoom viewfinder are also known.[0003]As an example of an objective lens forming such a real-image zoom viewfinder, one substantially includes, in order from the object side, a first lens group having a negative refractive power, a second le...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B15/14
CPCG02B15/14G02B13/0065G02B13/009G02B23/145G03B13/06G02B15/143507
Inventor SATO, KENICHI
Owner FUJIFILM CORP
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