Variable focal length optical system

Details Variable focal length optical system Variable focal length optical system

1996-09-25

1998-05-05

Nelms, David C.

Optical: systems and elements

Lens

With variable magnification

359684, 359714, 359764, 359773, G02B 1514, G02B 302, G02B 960, G02B 934

Patent

active

057483833

ABSTRACT:
In a variable focal length optical system which has, in succession from an object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, a third lens unit G3 having a positive refractive power, a fourth lens unit G4 having a positive refractive power, and a fifth lens unit G5 having a negative refractive power, when the focal length is varied from the maximum wide-angle state to the maximum telephoto state, at least the fifth lens unit G5 moves toward the object side, so that a first variable air gap between the first lens unit G1 and the second lens unit G2 increases, a second variable air gap between the second lens unit G2 and the third lens unit G3 decreases, a third variable air gap between the third lens unit G3 and the fourth lens unit G4 increases, and a fourth variable air gap between the fourth lens unit G4 and the fifth lens unit G5 decreases, the second lens unit G2 at least has a negative sub lens unit G21 which is disposed at a position closest to the object side and has a negative refractive power, and a sub lens unit G22 which is disposed in the neighborhood of the image side of the negative sub lens unit G21, and the optical system satisfies the following conditions:

REFERENCES:
patent: 5042927 (1991-08-01), Ogawa et al.
patent: 5126883 (1992-06-01), Sato et al.
patent: 5185678 (1993-02-01), Arimoto
patent: 5241421 (1993-08-01), Endo et al.
patent: 5440430 (1995-08-01), Sato
patent: 5606460 (1997-02-01), Ohtake

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