Abstract A zoom lens, having a diaphragm and comprising four coaxial lens components spaced axially from one another, includes a first component movable for focussing and a second component movable for zooming in front of the diaphragm, and includes a third component movable with the second component and a fourth stationary component behind the diaphragm. When zooming is performed, the diaphragm is shifted while the position of the exit pupil of the diaphragm produced by the third component is maintained fixed with respect to the fourth component. The aperture of the shifted diaphragm is simultaneously adjusted so as to maintain constant the diameter of the exit pupil during the zooming, thereby compensating the variation of F-number caused by the shifting. With this arrangement, it is possible to relatively decrease the diameter of the front lens member with a decrease in aberrations, because the diaphragm may be placed at a short distance, heretofore unattainable, from the center of the complete objective. The axial pencil that can pass through the fixed exit pupil is maintained unchanged in the fourth component with respect to the angular extent during the zooming so that aberrations of higher order can be stabilized by a suitable design of the fourth component throughout the entire zooming range. The zoom objective is usable with a color television camera by disposing its beam splitting system behind the fourth component, because the variation of color shading is not effected by the zooming.
An optical objective of the zoom type comprising, in combination, a focussing lens group; a lens group movable, for zooming, along the optical axis; a relay lens group; and a variable aperture diaphragm arranged within said movable lens group for shifting relative to a component of said movable lens group with adjustment of its aperture during such relative shifting to compensate the variation of the aperture ratio caused by shifting of said diaphragm; said component of said movable lens group, during such relative shifting, correcting the image of said diaphragm to maintain said image substantially constant in position relative to said relay lens group.
Claim 2
Dependent Claim
104 words
An optical objective of the zoom type comprising, in combination, a focussing lens group; a lens group movable, for zooming, along the optical axis; a relay lens group; and a variable aperture diaphragm arranged within said movable lens group for shifting relative to a component of said movable lens group with adjustment of its aperture during such relative shifting to compensate the variation of the aperture ratio caused by shifting of said diaphragm; said component of said movable lens group, during such relative shifting, correcting the image of said diaphragm to maintain said image substantially constant in position relative to said relay lens group.
Claim 3
Dependent Claim
42 words
An optical objective of the zoom type according to claim 1, wherein said movable lens group consists of a front lens member of negative power and a rear lens member of positive power, and said diaphragm is located between said two members.
Claim 4
Dependent Claim
43 words
An optical objective of the zoom type according to claim 1, wherein said movable lens group consists of a front lens member of negative power and a rear lens group of negative power, and said diaphragm is located between said two lens members.