A chum chucker is a chum distributing device 30. Then, random numbers which have not a periodicity due to 1f characteristics of the first and second noises are generated from the difference signal. The attachment element and the supporting element are furthermore arranged such that the attachment element remains fastened to the camera device during the displacement of the supporting element between its storage position and its active position. An air inlet is defined in the bottom wall. In this process, a specified coefficient that is defined in accordance with the base leak hole is taken into consideration.