An elongate tape element and method of manufacturing flexible pipe body are disclosed. When the fluid level detecting apparatus detects that the fluid level has reached a minimum fluid level, an ECU issues a warning. Furthermore, the synchronous linear motor can be provided with absolute and incremental positional measuring systems, such that the coarse resolution of the absolute measuring system can be supplemented by the fine resolution of the incremental system. The aperture sizes of the diaphragm at outside the specified range are used at least for one of the following: automatic exposure adjustment, auto focus adjustment, electronic zoom, displaying a moving image, taking for recording the moving image, and taking under a low resolution by thinning out pixels.