Photographing lens system
AssigneeCasio Computer Co., Ltd.
InventorEtsuro Kawakami
Life of this patent
Estimating the term…
Abstract
A photographing lens system includes an aperture stop, a first lens group, a second lens group, and a third lens group, in this order from the object. The first lens group includes a positive first lens element, and a negative second lens element which is cemented to or separate from the positive first lens element. The second lens group only includes a positive third lens element having an aspherical surface formed on at least one refractive surface thereof. The third lens group only includes a negative fourth lens element having an aspherical surface formed on at least one refractive surface thereof.
Claims12
A photographing lens system comprising an aperture stop, a first lens group, a second lens group, and a third lens group, in this order from an object side;
- wherein said first lens group comprises a positive first lens element, and a negative second lens element that is cemented to or separate from said positive first lens element;
- wherein said second lens group comprises a positive third lens element having an aspherical surface formed on at least one refractive surface thereof;
- wherein said third lens group comprises a negative fourth lens element having an aspherical surface formed on at least one refractive surface thereof;
- and
- wherein said photographing lens system satisfies condition (1) with respect to the power of said first lens group, and satisfies condition (2) with respect to the dimensions of the entire photographing lens system along the optical axis:
- 0.8<fI/f<2.8 (1)
- TL/f<1.7 (2)
- wherein
- f designates the focal length of the entire photographing lens system;
- fI designates the focal length of said first lens group;
- and
- TL designates the distance between the most object-side surface of said aperture stop and the image plane.
Dependencies are inferred from the claim text.