1. Field of the Invention
The present invention relates to a movement preventing structure for a color separation prism, and more particularly, to a movement preventing structure for a color separation prism which is applied to a camera apparatus having the color separation prism supported by a color separation prism supporting member whose length in an optical axis direction is changed by thermal expansion or contraction.
2. Description of the Related Art
Conventionally, there has been known various types of camera apparatuses for motion picture photography, each of which has a color separation prism supported by a color separation prism supporting member. The camera apparatus of this type has a problem in that the color separation prism supporting member thermally expands or contracts due to a change in outside air temperature at the time of photographing, and thereby the color separation prism is moved in an optical axis direction. There has been proposed a flange focal distance adjustment mechanism for always keeping a flange focal distance constant regardless of the change in ambient temperature (For example, refer to Japanese Patent Application Laid-Open No. 7-306349).
In the mechanism described in Japanese Patent Application Laid-Open No. 7-306349, the interval between a light receiving member attaching surface and a butting surface of a lens held by a lens frame, that is, the flange focal distance of lens is adjusted to a predetermined distance by urging the lens frame to position it at a predetermined position. Therefore, there arises a problem in that even if this mechanism is applied to various types of camera apparatuses for motion picture photography, each of which has a color separation prism supported by the color separation prism supporting member, the movement of the color separation prism cannot be prevented.