Retro-focus type wide angle lens
AssigneeSony Corporation
InventorYusuke Nanjo
Life of this patent
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Abstract
A retro-focus type wide angle lens has in succession from an object side a first negative meniscus lens having a convex surface facing the object side, a second positive lens, a third biconvex lens, a fourth negative doublet consisting of a biconvex lens and a biconcave lens, a fifth positive lens, and a sixth positive lens. Although this retro-focus type wide angle lens is formed of six lens groups and seven lens components, its field angle or angle of view is about 66.degree., its aperture ratio is 1:1.6, its total length is very short, the aperture of its first divergent lens group is very small and its various aberrations are satisfactorily compensated for.
Claims1
A retro-focus type wide angle lens system having an optical axis, an object side and an image side and an angle of view within the range of 60.degree. to 70.degree., comprising:
- in succession from the object side, a first negative meniscus lens component having a convex surface facing the object side;
- a second positive lens component;
- a third biconvex lens component;
- a fourth negative doublet component formed of a positive biconvex lens and a negative biconcave lens and having an object-side lens surface and an image-side lens surface;
- a fifth positive lens component having a convex surface facing the image side;
- and
- a sixth positive lens component having a convex surface facing the object side,
- the lens system satisfying the conditions:
- 1.3f<.vertline.f.sub.1 .vertline.<2f
- d.sub.2 +d.sub.3 +d.sub.4 <2f
- v.sub.2 <40
- 1.2<r.sub.7 /r.sub.9 <2
- where f.sub.1 is the focal length of said first lens component, d.sub.2 is the distance along the optical axis between said first and second lens components, d.sub.3 is the thickness along the optical axis of said second lens component, and d.sub.4 is the distance along the optical axis between said second and third lens components, v.sub.2 is an Abbe number of said second lens component, and r.sub.7 and r.sub.9 are curvature radii of said object-side and image-side lens surfaces, respectively, of said fourth lens component.
Dependencies are inferred from the claim text.