| 摘要 |
<p>A first blade includes two arms and four blades, and is arranged between a shutter base plate and an intermediate plate. A second blade includes two arms and four blades, and is arranged between the intermediate plate and an auxiliary base plate. During an exposure operation, the four blades of the first blade are brought into an overlap state from a development state and the four blades the second blade are brought into the development state from the overlap state. Since a contour forming edge of the intermediate plate above the opening portion is formed in the shape of an arc, the four blades of the second blade are able to start an operation appropriately from the overlap state.</p> |
