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US RE30,708 EGranted
Telephoto objective
AssigneeCanon Kabushiki Kaisha
InventorKikuo Momiyama
Life of this patent
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AssigneeCanon Kabushiki Kaisha
InventorKikuo Momiyama
Estimating the term…
A telephoto objective comprising a stationary convergent front lens group and a rear lens group which includes a lens member axially movable for focusing behind a front lens member which remains stationary during focusing, and an operating mechanism therefor. In order to achieve excellent stability of the various aberrations and particularly spherical aberration throughout the focusing range, compensation for the residual aberrations introduced by the front lens group is concentrated in the stationary front member of the rear lens group, while the movable rear member is configured to provide minimized variation of aberrations by constructing these two members as being divergent with their front surfaces convex to the object. In this particular arrangement, the movable member is moved toward the image plane as the objective is focused from the position for an object at infinity to the position for a close object.
A telephoto objective of high speed adjustable focus comprising a front lens group which has a positive refracting power and remains stationary during focussing, and a rear lens group which is divided into two parts, of which one part is axially movable to effect focussing to suit differing object distances, wherein said movable part of said rear lens being located behind the other part which is stationary during focussing and wherein the characteristics of the various lens elements of said front and rear lens groups and their spatial relationships to each other are substantially of the proportions indicated by the numerical data in the following table, in which R designates the radii of curvature of the refracting surfaces identified by the corresponding subscript numerals and numbered from the front to the rear of the objective, the positive sign indicating that the surface is convex to the front and the negative sign that it is concave thereto, D designates the axial separations between successive refracting surfaces of the objective being numbered from the front to the rear;
A telephoto objective of high speed adjustable focus comprising a front lens group which has a positive refracting power and remains stationary during focussing, and a rear lens group which is divided into two parts of which one part is axially movable to effect focussing to suit differing object distances, wherein said movable part of said rear lens being located behind the other part which is stationary during focussing and wherein the characteristics of the various lens elements of said front and rear lens groups and their spatial relationships to each other are substantially of the proportions indicated by the numerical data in the following table:
A telephoto objective of high speed adjustable focus comprising:
A telephoto objective of high speed adjustable focus comprising:
A telephoto objective of high speed adjustable focus comprising a front lens group which has a positive refracting power and remains stationary during focussing, and a rear lens group which is positioned on the image side axially apart from said front lens group and has a negative refracting power, said rear lens group being divided into two parts of which one part is axially movable to effect focussing to suit differing object distance, and the other part has a negative refracting power and stationary during focussing.
A telephoto objective of high speed adjustable focus comprising:
Dependencies are inferred from the claim text.