To provide a variable power optical system whose entire length is small as compared with image height and whose aberration is good.
The variable power optical system includes, in order from an object side: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power. The second lens group includes at least: a positive lens; and a negative lens. The fourth lens group includes a positive lens. The variable power optical system satisfies 10≤Vd4g≤45, 2.2≤|α/f1|+(α/f2)-0.026×Vd4g≤5.0 and 10≤Vdmax-Vdmin≤80, wherein α=(FLw×FLt)1/2, FLw is a focal length at a wide angle end, FLt is a focal length at a telephoto end, f1 is a focal length of the first lens group, f2 is a focal length of the second lens group, Vd4g is an Abbe number of the positive lens in the fourth lens group for a d-line, Vdmax is an Abbe number of glass material having the lowest dispersion in the glass material of the second lens group, for the d-line, and Vdmin is an Abbe number of glass material having the highest dispersion in the glass material of the second lens group, for the d-line.
MIMURA TAKAYUKI
ADACHI YOJIN
GOTO HISASHI
| JP2005156828A | 2005-06-16 | |||
| JP2009069794A | 2009-04-02 | |||
| JP2008191308A | 2008-08-21 | |||
| JP2008129459A | 2008-06-05 | |||
| JP2005283648A | 2005-10-13 | |||
| JP2006208889A | 2006-08-10 | |||
| JP2008233611A | 2008-10-02 | |||
| JP2009058873A | 2009-03-19 |
Masayuki Fujinaka