| 摘要 |
PURPOSE:To reduce the loss of the quantity of light of a photographic lens system by forming a reverse projection image of a pupil-split mask on or nearby a luminous flux splitting and reflecting surface through a condenser lens and an image reforming lens. CONSTITUTION:Luminous flux which is projected by the reflecting surface 1, passed through a focus detection lens system 3, and imaged on an image plane 4 is converged by the condenser lens 6, and split by the pupil-split mask 7 to form images of a standard part and a reference part on a photodetecting element array 9 such as a CCD through a separator lens 8. The pupil-split mask 7 and reflecting surface 1 are arranged almost in conjugate relation with the condenser lens 6 and focus detection lens system 3 so that the image of the pupil-split mask 7 is projected reversely on the reflecting surface 1 through the focus detection lens system 3 and condenser lens 6. Therefore, the image of the pupil-split mask 7 is formed on or nearby the reflecting surface 1. Consequently, the loss of the quantity of light of the photographic lens system extending to an image pickup element can be reduced. |
