Two group zoom lens having weak front element

Details Two group zoom lens having weak front element Two group zoom lens having weak front element

2001-06-20

2003-02-25

Dang, Hung Xuan (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S692000

Reexamination Certificate

active

06525886

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to lens design, and in particular to a zoom lens for use in a camera.
BACKGROUND OF THE INVENTION
Compact, reasonably priced zoom lens for cameras are known. For example, U.S. Pat. No. 5,473,473 discloses a zoom lens having two plastic lens elements. The zoom lens includes a positive power lens element, a negative power lens element, and an aperture stop. While the zoom lens disclosed in U.S. Pat. No. 5,473,473 works extremely well for its intended purpose, plastic lenses having strong power are susceptible to a thermal reaction when exposed to changes in environmental operating conditions. This can cause a shifting of the image plane of the zoom lens relative to the rear (commonly referred to as last, etc.) element of the zoom lens.
As such, there is a need for a reasonably priced thermally stable (neutral, etc.) zoom lens that reduces shifting of the image plane relative to the rear element of the zoom lens caused by a thermal reaction of a plastic lens.
SUMMARY OF THE INVENTION
According to a feature of the present invention, a zoom lens includes, in order from an object side, a first lens group having a first lens element and a second lens element; and a second lens group having a third lens element. The zoom lens satisfies the following condition: |&phgr;
1
|/&phgr;
w
<0.003, where &phgr;
1
is a power of the first lens element and &phgr;
w
is a power of the zoom lens in a wide angle position.
According to another feature of the present invention, a zoom lens includes, in order from an object side, a first lens group having a first lens element and a second lens element; and a second lens group having a third lens element. The zoom lens satisfies the following condition: |&phgr;
1
|/&phgr;
w
<0.08, where &phgr;
1
is a power of the first lens element and &phgr;
w
is a power of the zoom lens in a wide angle position.
According to another feature of the present invention, a zoom lens includes, in order from an object side, a first lens group having a first lens element and a second lens element with the first lens group having a power and the second lens element having a power; and a second lens group having a third lens element, wherein the power of the first lens group is substantially equal to the power of the second lens element.


REFERENCES:
patent: 5270867 (1993-12-01), Estelle
patent: 5329401 (1994-07-01), Sato
patent: 5473473 (1995-12-01), Estelle et al.
patent: 5596453 (1997-01-01), Kim
patent: 5604639 (1997-02-01), Bietry et al.

Affiliated with

Also associated with

Rating

Two group zoom lens having weak front element does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Two group zoom lens having weak front element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two group zoom lens having weak front element will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3131528