Variable field curvature lens system
AssigneeMinolta Camera Kabushiki Kaisha
InventorHaruo Abe
Life of this patent
Estimating the term…
Abstract
An optical lens system is provided having the capability of selectively varying the peripheral field curvature to improve focusing for nonplanar objects and for special photographic effects. The lens system can include in sequence, a first lens group of positive refractive power, a second lens group of negative refractive power and a third lens group of positive refractive power. The specific refractive power of the first and second lens group are designed so that the optical ray traces from an object on the optical axis at infinity will run approximately parallel with the optical axis in the space between the second and third lens groups. The first and second lens groups being movable as a unit relative to the third lens group to change the field curvature without varying the back focal distance of the lens system.
Claims9
In a lens system for the normal transmission of flat images, the improvement of a variable field curvature capability comprising:
- at least a first lens element of positive refractive power positioned within the lens system to receive incident optical ray traces of an object at infinity that are approximately parallel with an optical axis of the lens system;
- a second lens element of negative refractive power located adjacent the image side of the first lens element;
- and
- a third lens element of positive refractive power located adjacent the image side of the second lens element, the relative refractive powers of the first and second lens elements being designed so that the optical ray traces from the object on the optical axis at infinity are approximately parallel with the optical axis in a space formed between the second and third lens elements, the first and second lens elements being movable as a unit relatively to the third lens elements for changing the field curvature of the lens system without varying the back focal distance of the lens system.
A variable field curvature lens system comprising three lens components within the following parameters;
- ______________________________________ Radius of Axial Refractive Abbe Curvature Distance Index Number ______________________________________ r.sub.1 0.2062 d.sub.1 0.0451 N.sub.1 1.6172 .nu..sub.1 54.0 r.sub.2 -4.5450 d.sub.2 0.0228 r.sub.3 -0.7751 d.sub.3 0.0177 N.sub.2 1.6206 .nu..sub.2 38.3 r.sub.4 0.2014 d.sub.4 0.0925 r.sub.5 1.2638 d.sub.5 0.0462 N.sub.3 1.6172 .nu..sub.3 54.0 r.sub.6 -0.7462 ______________________________________
Dependencies are inferred from the claim text.