VARIABLE MAGNIFICATION OPTICAL SYSTEM AND IMAGE-CAPTURING DEVICE

摘要

[Problem] To satisfactorily correct chromatic differences of magnification in a variable magnification optical system when an extender is inserted. [Solution] This variable magnification optical system comprises: a relay lens group (fifth lens group (G5)) comprising a relay front group (G5f) and a relay rear group (G5r) that are separated from one another by a predetermined air space, the relay lens group being fixed when the magnification is varied and having an image-forming effect; and an extender lens group (Ext) that is provided insertably/removably between the relay front group (G5f) and the relay rear group (G5r) and that extends the focal distance toward the telephoto side without changing the image-forming position. The extender lens group (Ext) comprises, in order from the object side: a first lens group (EG1) having a positive refractive power; and a second lens group (EG2) having a negative refractive power. The second lens group (EG2) is a cemented lens comprising, in order from the object side: a convex-meniscus lens (EL21); a biconcave lens (EL22); and a convex-meniscus lens (EL23).