| 摘要 |
PURPOSE:To obtain a zoom lens having a compact zoom system and imaging system, small front lens diameter, good aberration correction and exceptionally high contrast by attaining the aberration correction and compactness with the 4th component and the 5th component. CONSTITUTION:The conditions of the equations are satisfied where the radius of curvature of the i-th lens counted from the object side of the lenses for the 4th lens component and the 5th lens component of the zoom lens is designated as Ri, the spacing of the i-th lens as di, the Abbe number of the glass of the i-th lens as nui, the combined focal length of the front lens group of the 5th lens component as fF, the combined focal length of the rear lens group of the 5th lens component as fR and the combined focal length of the 5th lens component as f5. The condition 1 controls the convergent effect of the two positive lenses of the 4th component in the stage of making said component afocal while suppressing the generation of an aberration. The condition 2 is intended to remove the chromatic aberration of the focal luminous flux by giving a large Abbe number to the two positive lenses of the 4th lens component. The condition 3 indicates the ratio of the respective combined focal lengths of the front and rear groups of the 5th lens component. The condition 4 gives a strong curvature to R12 which is the only lens having a divergent effect in the rear group. The condition 5 assists the effect of the R12 and balances the correction of the comatic aberration and curvature of field. |
