PROBLEM TO BE SOLVED: To provide an optical system for observation capable of having a small number of space intermediately formed images, suppressing loss in the amount of light reaching an imaging element, and forming bright and clear images, and an imaging apparatus including the same.SOLUTION: An optical system for observation includes, in order from an object side, an object lens and an imaging lens. A focus group, which is moved in an optical direction in accordance with a change in an object distance for focusing, is provided in the imaging lens. The object lens reduces the size of a subject image to make it incident on the surface of a space intermediately formed image. The imaging lens enlarges the space intermediately formed image and re-forms it on the imaging element.SELECTED DRAWING: Figure 1aCOPYRIGHT: (C)2016,JPO&INPIT【課題】空間中間結像の数が少なく、撮像素子に到達する光量損失を抑え、明るく鮮明な画像を形成することができる観察用光学系及びそれを備えた撮像装置を提供すること。【解決手段】物体側から順に、対物レンズと、結像レンズとを持ち、前記結像レンズ中に物体距離の変動に応じて光軸方向に移動させてフォーカシングさせるフォーカス群を具備し、前記対物レンズは被写体像を縮小して空間中間結像面に入射させ、前記結像レンズでは前記空間中間結像を拡大して撮像素子上に再結像させる観察用光学系。【選択図】図1a
