Photography – Having variable focal length of camera objective – Power zoom
Reexamination Certificate
1999-10-18
2001-08-21
Perkey, W. B. (Department: 2851)
Photography
Having variable focal length of camera objective
Power zoom
C396S349000, C396S448000, C359S696000
Reexamination Certificate
active
06278844
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical apparatus, such as a camera, capable of moving an optical system between a usage position and a stowage position.
2. Description of Related Art
In conventional cameras performing a magnification-varying action and a focus-adjusting action by moving a plurality of lens groups in the optical axis direction, there is known a camera which is arranged to move the lens groups to a stowage position in which the lens groups are stowed within a camera body when the camera is not being used for photo-taking, so as to improve the portability of the camera. Such a so-called lens-barrel-stowable type zoom camera is designed, in general, for photography for use with 35 mm film or the like.
Unlike the prior known example described above, cameras using solid-state image pickup elements, such as video cameras and electronic still cameras, because of necessarily having a low-pass filter, a color correction filter and other optical members disposed between the most rear end of the lens and the image pickup element, have the necessity of using a lens having a relatively-long back focal distance. Further, in the case of using the image pickup elements for colors, to avoid occurrence of colored shadings, it is desired that the lens has good telecentric characteristics in the image space.
With the requirements of elongating the back focal distance and of making the telecentric characteristics good, when fulfilling them at once, a lens system is proposed in which, for the zooming purposes, the front lens element is moved in a reciprocating fashion with the locus convex toward the image side.
However, with the use of such a lens system, to make up the so-called stowable type lens barrel, a necessity arises in that the lens barrel is first monotonously drawn out from the stowage position to the photo-taking position and, upon arrival at the photo-taking position, the drawing direction of the lens barrel is reversed. For this reason, the lens barrel has to be made large. Moreover, as the completion of the drawing movement of the lens barrel is immediately followed by the start of the reverse movement for the magnification-varying action, there is a high possibility of causing an increase of driving load.
BRIEF SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, there is provided an apparatus, such as an image pickup apparatus, comprising an optical unit, and an operating device which brings the optical unit to a usage start position by drawing in the optical unit after drawing out the optical unit from a stowage position, the operating device causing a focal-length varying operation to be performed by further drawing in the optical unit from the usage start position, so that it is possible to adequately perform the focal-length varying operation after the optical unit is moved from the stowage position to the usage start position.
REFERENCES:
patent: 5905918 (1999-05-01), Nakamura et al.
Canon Kabushiki Kaisha
Perkey W. B.
Robin Blecker & Daley
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