Zoom lens, camera, and portable information terminal apparatus
AssigneeRicoh Company, Ltd.
InventorMakoto Hirakawa
Life of this patent
Estimating the term…
Abstract
A lens (1), a lens (2) and a lens (3) constitute a first group of lenses, a lens (4), a lens (5), a lens (6) and a lens (7) constitute a second group of lenses, and a lens (8) constitutes a third group of lenses in a zoom lens of the present invention. The second group of lenses is constituted by a first positive lens (4), a negative lens (5) which is in a meniscus shape which faces its convex shape toward a side of an object (70), a second positive lens (6) in a meniscus shape which faces its convex shape toward the object (70) side, and the third positive lens (7), which are in order from the object (70) side.
Claims2
A zoom lens comprising:
- a first group of lenses, a second group of lenses and a third group of lenses which are subsequently arranged from a side of an object to a side of an image;
- said first group of lenses having a negative refractive power, said second group of lenses having a positive refractive power and said third group of lenses having a positive refractive power;
- an aperture stop provided at the object side of said second group of lenses;
- a first positive lens;
- a negative lens;
- a second positive lens;
- and
- a third positive lens
- said first positive lens, negative lens, second positive lens, and third positive lens being subsequently arranged from the object side to the image side in said second group of lenses, wherein
- when a zooming from a short focal end to a long focal end is carried out, said second group of lenses monotonously moves from the image side to the object side, and said first group of lenses moves so as to correct a displacement of a position of image plane in accordance with the zooming;
- and
- at least said third positive lens positioned nearest to the image side is a plastic aspheric lens.
2-10. (Canceled)
Dependencies are inferred from the claim text.