| 摘要 |
PURPOSE:To ensure the ultra-closeup photogaphy with good image forming performance, by forming a relay lens with a front group and a rear group, forming the rear group with positive and negative lens groups along with the lenses preceding the positive lens group formed into an afocal system as a whole and shifting forward the positive lens group. CONSTITUTION:A focusing lens group G1 having positive refractive power, a variable magnification lens group G2 having negative refractive power, a compensator group G3 of negative refractive power and a relay lens group G4 consisting of front and rear groups G41 and G42 are set successively from the side of a subject. The group G42 contains a negative lens group GN and a positive lens group GP from the side of the subject, and the lenses preceding the group GP are formed into an afocal system as a whole. Then the group GP is set close to the front lens system along the optical axis as shown in the figure. Thus the ultra-closeup shooting is carried out over the entire zooming range. In this case, no variation is virtually produced for the spherical aberration owing to the shift of the group GP along with reduced variations of other aberrations. |
