Close-up photographing lens

Details Close-up photographing lens Close-up photographing lens

1998-11-16

2000-09-26

Sugarman, Scott J.

Optical: systems and elements

Lens

Reverse telephoto

359753, G02B 1304

Patent

active

061249904

ABSTRACT:
A close-up photographing lens (10) having a long back focus and a large aperture, thus making the lens suitable for use with high-performance electronic imaging equipment. The lens comprises, objectwise to imagewise, a first lens group (G1) having positive refractive power, a second lens group (G2) having positive refractive power, and a relay optical system (GL) having positive refractive power. The relay optical system includes a third lens group (GLN) having negative refractive power and a fourth lens group (GLP) having positive refractive power. The first lens group and the second lens group are separated by an axial air space (D12) and move objectwise on different trajectories (16,18) when changing focus from an infinite focus state to a most close-up focus state. The axial air space is narrower in the most close-up focus state than in the infinite focus state. The lens preferably satisfies at least one of a number of design conditions.

REFERENCES:
patent: 4178076 (1979-12-01), Tsuji et al.
patent: 4621909 (1986-11-01), Hamanishi
patent: 5331465 (1994-07-01), Miyano

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