Camera using cartridge which can be replaced in the course of usage

摘要

A camera of this invention detects the presence or absence of magnetic data and prevents at least occurrence of a frame of double exposure or unexposed frame even under the influence of an electromagnetic noise. The position of a perforation of a film is detected by a position detecting section and whether a magnetic head is set in contact with a recording area adjacent to an exposed frame or a recording inhibition area adjacent to a portion between the adjacent exposed frames is determined. A threshold value used for determining the presence or absence of magnetic data is set in a threshold setting circuit based on an output generated when the position detecting circuit determines that the magnetic head is set in contact with the recording inhibition area. An output of the magnetic head is compared with the threshold value by a determination circuit and the presence or absence of magnetic data in the recording area is determined when the position detecting circuit determines that the magnetic head is set in contact with the recording area. Whether the operation of the magnetic head is permitted or inhibited is determined based on an output of the determination circuit.