Sony Corporation

Hiroshi Omichi

Motoyuki Ohtake

Hiroki Hagiwara

Masayuki Murata

Atsuo Minato

Sota Miyatani

Kazuki Yonemoto

A zoom lens includes, from the object side, a positionally-fixed first lens group having a positive refracting power, a second lens group having a negative refracting power and movable in an optical axis direction for zooming, a third lens group having a positive refracting power, and a fourth lens group movable in the optical axis direction. The first lens group includes a negative lens, a positive lens and another positive lens disposed in order from the object side and satisfies15.0&#x3c;&#x3c;31.0&#x2003;&#x2003;(1)7.0&#x3c;1/&#x3c;13.0&#x2003;&#x2003;(2)&#x2212;8.5&#x3c;1/&#x3c;&#x2212;4.0&#x2003;&#x2003;(3)where fw and ft are the focal lengths of the entire lens system in a wide angle end state and a telephoto end state, respectively, f1 is the focal length of the first lens group, and fL1 is the focal length of the negative lens of the first lens group.

Zoom lens and image pickup apparatus

A vari-focal length lens system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. In the second lens group, each of the object-side surface of the negative lens arranged on the object side and the object-side surface of the positive lens is formed in an aspherical shape and satisfies the following conditional expression:2.0&#x3c;1/()&#x3c;2.5wherein

Variable focal length lens system image pick up apparatus

A variable focal length lens system includes first to fourth lens groups which have positive, negative, positive, and positive refractive powers, respectively, and are arranged in this order from an object side to an image side. An aperture diaphragm is arranged in the vicinity of the third lens group. The variable focal length lens system satisfies the following Conditional expressions 1 and 2:&#x2212;0.04&#x3c;23&#x3c;0.18, and&#x2003;&#x2003;[Conditional expression 1]0.48&#x3c;24&#x3c;0.72&#x2003;&#x2003;[Conditional expression 2]

Variable focal length lens system and imaging apparatus

A zoom lens having a plurality of lens groups which performs zooming by changing distances between groups includes a reflective member to bend an optical axis which passes through the plurality of the lens groups. The plurality of lens groups includes, in order from an object side to an image plane side: a first lens group having a positive refractive power and fixed in position; a second lens group having a negative refractive power and to be moved along the optical axis direction when zooming; a third lens group having a positive refractive power and fixed in position; a fourth lens group having a positive refractive power and to be moved in the optical axis direction to compensate a position change of the image plane when zooming and focusing; and a fifth lens group having a negative refractive power and fixed in position when zooming. A ratio of the focal distance of the third lens group and the focal distance of the whole lens system is in a range of 3.4 to 4.0.

Zoom lens and image pick-up apparatus

A zoom lens includes 10 or less lens elements and having a zoom ratio of more than 20&#xd7;, said zoom lens having first, second, third, and fourth groups of lens elements placed in turn from object side to image side; wherein the first group of lens elements has positive refractive power and is fixed in position during zooming; wherein the second group of lens elements has negative refractive power and is moved in position during zooming; wherein the third group of lens elements has positive refractive power, includes at least one aspheric surface, and is fixed in position during zooming; wherein the fourth group of lens elements has positive refractive power, includes at least one aspheric surface, corrects variations in image surface position during zooming, and performs focusing; and wherein the zoom lens satisfies the following conditional expression (1): where dz is the movable distance of the second group of lens elements to perform zooming and fw is the focal distance of the whole lens system at a wide angle end.

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Tokyo, Japan

Hiroshi Omichi