Internal focusing zoom lens with means preventing lens warping effects
First Claim
1. An internal focusing zoom lens which performs focusing by extending, forward and backward, a movable focus lens group provided behind a fixed focus lens group, said internal focusing zoom lens comprising:
- a first fixing lens barrel in which a helicoid is formed to extend said movable focus lens in the direction of the optical axis;
a focusing lens barrel supporting said movable focus lens group and connecting to said first fixing lens barrel in such a manner as to move forward and backward;
a second fixing lens barrel in which a fixed focus lens frame for supporting said fixed focus lens frame is fixed at a point thereof; and
wherein when at least one of a lens hood, a wide convertor lens or a tele-convertor lens is attached to said second fixing lens barrel, said second fixing lens barrel is warped, but said helicoid of said first fixing lens barrel is not warped.
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Accused Products
Abstract
A helicoid is formed at the outer periphery of the front of a body fixing lens barrel, and a helicoid is formed at the inner periphery of the back of the focusing lens barrel in such a manner that these two helicoids can be engaged with each other. A movable focusing lens group is held by the front of the focusing lens barrel so that the helicoid can be pushed to one side and the inaccurateness of the focus can be reduced. A lens hood is attached to a fixed focus lens frame fixed to a focus fixing lens barrel, which is different from the body fixing lens barrel. Thereby, even if the focus fixing lens barrel is deformed by the force generated by the attachment, the deformation does not warp the helicoid.
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Citations
12 Claims
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1. An internal focusing zoom lens which performs focusing by extending, forward and backward, a movable focus lens group provided behind a fixed focus lens group, said internal focusing zoom lens comprising:
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a first fixing lens barrel in which a helicoid is formed to extend said movable focus lens in the direction of the optical axis; a focusing lens barrel supporting said movable focus lens group and connecting to said first fixing lens barrel in such a manner as to move forward and backward; a second fixing lens barrel in which a fixed focus lens frame for supporting said fixed focus lens frame is fixed at a point thereof; and wherein when at least one of a lens hood, a wide convertor lens or a tele-convertor lens is attached to said second fixing lens barrel, said second fixing lens barrel is warped, but said helicoid of said first fixing lens barrel is not warped. - View Dependent Claims (2, 3, 4)
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5. An internal focusing zoom lens which performs focusing by extending, forward and backward, a movable focus lens group provided behind a fixed focus lens group, said internal focusing zoom lens comprising:
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a first fixing lens barrel in which a helicoid is formed to extend said movable focus lens in the direction of the optical axis; a focusing lens barrel which supports said movable focus lens group, and in which a helicoid engaged with said helicoid of said first fixing lens barrel, said focusing lens barrel connecting to said first fixing lens barrel in such a manner as to move forward and backward; a second fixing lens barrel in which a fixed focus lens frame for supporting said fixed focus lens frame is fixed at a point thereof; and wherein when at least one of a lens hood, a wide convertor lens or a tele-convertor lens is attached to said second fixing lens barrel or said fixed focus lens frame fixed to said second fixing lens barrel, said second fixing lens barrel is warped, but said helicoid of said first fixing lens barrel is not warped. - View Dependent Claims (6, 7, 8, 9, 10)
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11. An internal focusing zoom lens which extends a movable focus lens group provided behind a fixed focus lens group in a direction of an optical axis;
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a fixing lens barrel provided with an extending mechanism for extending said movable focus lens group in the direction of said optical axis; a focusing lens barrel supporting said movable focus lens group, having an engaged section engaged with said extending mechanism, and connecting to said fixing lens barrel in such a manner as to move forward and backward, said focusing lens barrel supporting said movable focus lens group so that a center of gravity of said movable focus group is shifted away from said engaged section in a direction of said optical axis; and wherein said extending mechanism and said engaged section are pushed to one side by said shifting of the center of gravity so that they contact each other in a manner eliminating looseness. - View Dependent Claims (12)
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Specification