Photography – With exposure objective focusing means – focusing aid – or... – Mechanical mechanism for displacement of exposure objective
Reexamination Certificate
2002-09-27
2004-05-11
Adams, Russell (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Mechanical mechanism for displacement of exposure objective
C396S432000, C359S412000
Reexamination Certificate
active
06735385
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a viewing apparatus which includes a viewing optical system (e.g., a viewing optical system of a telescope or a binocular) and a photographing optical system for photographing an object viewed through the viewing optical system, wherein a distant object can be viewed through the viewing optical system, and recorded as image data at the same time.
2. Description of the Prior Art
Telescopes and binoculars are known as viewing apparatuses for viewing distant objects. However, such conventional viewing apparatuses do not have a function of recording object images which are viewed therethrough. Although there have been various proposals of combining a viewing apparatus such as a telescope or a binocular with a camera to achieve such an image recording function, none of these proposals are practical for ordinary users due to, for example, an unavoidable increase in size of the viewing apparatus.
The ideal magnification of a binocular for general use is approximately seven times (×7). This degree of magnification is advantageous for viewing a distant object closely with a decreased influence in hand shake. Nevertheless, the field of view of a binocular corresponds to that viewed through a long-focus telephoto lens system of over 300 mm attached to a 35 mm camera. Accordingly, if the function of recording an image viewed through a binocular is achieved simply by combining a typical binocular with a conventional camera, the system becomes bulky.
In addition, the photographing lens system of such a multi-function viewing apparatus is required to have a high optical performance if high-resolution object images are to be recorded. This inevitably increases the number of lens elements to thereby increase the cost of production and the weight of the entire optical system.
In such a multi-function viewing apparatus, to maintain adequate operability as a viewing apparatus, it is desirable for the focusing mechanism of the photographing optical system to operate in association with the focusing operation of the binocular. However, in a long-focus telephoto lens system such as the aforementioned long-focus telephoto lens system having a focal length of over 300 mm, it is impossible to achieve a focusing operation with a sufficient degree of accuracy simply by the focusing mechanism of the photographing optical system operating in association with the focusing operation of the binocular since such a long-focus telephoto lens system is required to be focused on viewing objects with a high degree of accuracy.
In a focusing operation of a viewing apparatus, it is normally the case that a user visually finds a sharp focal point on an object image while manually operating the apparatus. However, vision varies greatly between individuals, and accordingly, the focal point varies greatly between individuals.
SUMMARY OF THE INVENTION
The present invention provides a viewing optical system having both a distant-object viewing function and a distant-object image recording function with a low cost of production without increasing the size of the optical system, and further provides such a viewing optical system which achieves easy operability in a focusing operation.
As an aspect of the invention, a viewing apparatus having a photographing function is provided, including a viewing system having a viewing optical system, the viewing optical system having a positive objective optical system and an eyepiece optical system, an image of an object formed through the positive objective optical system being viewed through the eyepiece optical system; and a photographing system including a photographing optical system for photographing the object viewed through the eyepiece optical system, the photographing optical system being provided independently of the viewing optical system. The photographing optical system includes a first lens group and a second lens group. The photographing system includes two focusing mechanisms, which operate independently from each other, for changing both absolute positions of the first lens group and the second lens group and a relative position of the first lens group and the second lens group on an optical axis of the photographing optical system.
It is desirable for the first lens group and the second lens group to be arranged in that order from an object, the two focusing mechanisms moving the first lens group and the second lens group along the optical axis independent of each other to shift an image of the object to a predetermined point. It is also desirable for the following conditions (1) and (2) to be satisfied:
0.1<f
t
/f
0
<0.7 . . . (1)
0.4<|T
I
/T
II
|<2.5 . . . (2)
wherein
“f
t
” represents the focal length of the photographing optical system,
“f
0
” represents the focal length of the positive objective optical system of the viewing optical system,
“T
r
” represents the traveling distance of the first lens group necessary for achieving focus from an infinite distance to a finite object distance, and
“T
II
” represents the traveling distance of the second lens group necessary for achieving focus from an infinite distance to the finite object distance.
It is desirable for the eyepiece optical system to have a positive power, wherein the following condition (3) is satisfied:
5<f
0
/f
e
. . . (3)
wherein
“f
0
” represents the focal length of the objective optical system of the viewing optical system, and
“f
e
” represents the focal length of the eyepiece optical system of the viewing optical system.
The reason why the viewing optical system can be prevented from increasing in size while satisfying conditions (1) through (3) (even though the focal length of the photographing optical system in particular is shortened) is that digital cameras using an image pick-up device (e.g., CCD) instead of conventional cameras using a silver-halide film have become popularized in recent years. The scale of integration of the CDD has increased rapidly; the size of the image plane (picture plane) of a typical CCD is approximately one tenth of the size of a conventional 35 mm film frame. Moreover, even if the focusing mechanism of the photographing optical system operates in association with the focusing mechanism of the viewing optical system, a sufficiently high focusing sensitivity can be obtained by making the focal length of the photographing lens system shorter than the focal length of the objective optical system of the viewing optical system. Furthermore, providing the viewing optical system with a focus system for independently moving the first and second lens groups along the optical axis to shift an image focal point of an image of a viewing object to a given point makes it possible to correct deviation of the focal point set by a manual operation of the user with an auxiliary device such as an autofocus system.
The viewing system can include a first focusing mechanism for moving at least one optical element of the viewing optical system along the optical axis to shift an object image formed by the photographing optical system to a given point to focus the viewing system on the object, a second focusing mechanism for moving one of the first lens group and the second lens group to shift an image formed by the photographing optical system, and an association mechanism which interconnects the first focusing mechanism with the second focusing mechanism to allow the first focusing mechanism to operate in association with the second focusing mechanism.
The viewing system can include a telescope, wherein the eyepiece optical system has positive power, and wherein an image formed through the positive objective optical system is viewed through the positive eyepiece optical system.
As another aspect of the invention, a viewing apparatus having a photographing function is provided, including a viewing system having a pair of viewing optical systems, each of the pair of viewing optical systems having a positive objective optical system and
Adams Russell
Greenblum & Bernstein P.L.C.
PENTAX Corporation
Smith Arthur
LandOfFree
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