| 摘要 |
PURPOSE:To ensure high brightness even at the four corners of a film, by setting an optical panel comprising a number of prisms having different angles in the horizontal and vertical directions as the front of a light emitting part of a photographic flash device and accordingly, obtaining the elliptic light distribution properties to increase the light efficiency. CONSTITUTION:The valley angle is set at P for a section form formed by a line A-A' of an optical panel 2, and the valley angle is set at Q for the section form formed by a line B-B'. Then P<Q is satisfied. Such panel 2 is mounted to the front of the light emitting part of a photographic flash device. As a result, the horizontal light diffusion ratio becomes larger than the vertical light diffusion ratio. Thus the light distribution is formed into an ellipse to increase the brightness at four corners of a film without reducing the central light volume. |
