JP2007121748A5 - - Google Patents

Claims (8)

In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having positive refractive power, a third lens unit having positive refractive power, constituted by four lenses as a whole system In zoom lenses that perform zooming by changing the interval between lens groups,
When i is shown as an order counted from the object side, the focal length of the i-th lens unit is fi, the focal length of the entire system at the wide-angle end is fw, and the focal length of the entire system at the telephoto end is ft. −0.85 < f1 / f2 <−0.7
1.6 <ft / fw
A zoom lens characterized by satisfying the following conditions:   During zooming from the wide-angle end to the telephoto end, the first lens group has a convex locus on the image side so that the distance between the lens groups at the telephoto end is smaller than that at the wide-angle end. The zoom lens according to claim 1, wherein the lens group moves from the image side to the object side.   The first lens group is composed of a single negative lens having concave concave surfaces, and the second lens group is composed of a single meniscus positive lens. Zoom lens.   4. The zoom lens according to claim 1, wherein the third lens group includes a positive lens and a negative lens, and the most image-side surface has a convex shape on the image side.   The zoom according to any one of claims 1 to 4, wherein a stop is disposed on the object side or the image side of the second lens group, and the stop moves together with the second lens group during zooming. lens.   The zoom lens according to any one of claims 1 to 5, wherein a distance on the optical axis from the first lens surface on the object side to the image plane is 15 mm or less. When i is shown as the order counted from the object side and the refractive index for the d-line of the material of the i-th lens is Ndi, Nd1 <1.55
Nd2 <1.70
Nd3 <1.55
The zoom lens according to claim 1, wherein the following condition is satisfied.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup device that receives an image formed by the zoom lens.