AUTOMATIC FOCUSING DEVICE

摘要

PURPOSE:To effectively utilize the inside space of a camera to reduce the size of the camera and to improve the detection accuracy of focus detection by branching the luminous flux of a primary imaging path and forming the image magnified by a magnifying lens to a focus detecting element provided in the upper space of a filter. CONSTITUTION:Photographing light is imaged to a focal plate 7 and is reflected by a finder mirror 9 so as to be formed as an aerial image on a secondary imaging plane 12. Said luminous flux is branched by a beam splitter 4 and is entered to the focus detecting element 5. The imaging is enlarged by a concave lens 3 to improve the accuracy of the focus detection. The space around the shutter is effectively utilized by providing the element 5 to this position. Part of the luminous flux is received in a photodetecting part 10 through the half-mirror 9a to measure the luminance of a subject. Photographing information is displayed on the display part 14 of the imaging plane 12 to prevent the incident of light from the display part to the photodetecting part 10. The detecting element 5 and the photodetecting part 10 are provided in the cavity of the camera in such a manner, by which the size of the camera is reduced and the accuracy of the focus detection is improved.