Variable magnification optical system, image pickup device and digital apparatus
AssigneeKonica Minolta Opto, Inc.
InventorKeiji Matsusaka
Life of this patent
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Abstract
A variable magnification optical system of the present invention and an image pickup device and a digital apparatus including this are provided with a four-component optical system of negative-negative-positive-negative arrangement, wherein a first lens group thereof includes only one negative lens as a lens having an optical power, and a third lens group thereof satisfies a conditional expression of 1.4<β3t/β3w<4 when β3t and β3w respectively denote image magnifications of the third lens group at a telephoto end and at a wide-angle end. The variable magnification optical system, the image pickup device and the digital apparatus having such a construction can be further downsized.
Claims24
A variable magnification optical system, comprising a first lens group having a negative optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a fourth lens group having a negative optical power successively from an object side to an image side, wherein:
- the first lens group includes only one negative lens as a lens having an optical power, and
- the third lens group satisfies the following conditional expression (1):
- 1.4<β3t/β3w<4 (1)
- where β3t denotes an image magnification of the third lens group at a telephoto end and β3w denotes an image magnification of the third lens group at a wide-angle end.
A variable magnification optical system, comprising a first lens group having a negative optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a fourth lens group having a negative optical power successively from an object side to an image side, wherein:
- the first lens group includes only one negative lens as a lens having an optical power, and
- the third lens group satisfies the following conditional expression (2):
- 1.5<(β3t/β3w)/Z<2 (2)
- where β3t denotes an image magnification of the third lens group at a telephoto end, β3w denotes an image magnification of the third lens group at a wide-angle end and Z denotes a zoom ratio of the entire system.
Dependencies are inferred from the claim text.