Camera capable of measuring power source voltage

Abstract

A battery check device for a camera which includes a discharging circuit to which current flows from a battery and a discharging time setting device for setting a discharging time for determining that an internal resistance of the battery has increased due to non-use of the battery so as to temporarily reduce an output voltage of the battery. The discharging time set by the discharging time setting device is longer than a time required to check the residual energy amount of the battery. A determining device determines whether a voltage of the discharging circuit has reached a reference voltage specific to the battery within the discharging time. It is determined that the residual energy amount of the battery is sufficient and that the internal resistance of the battery has merely increased due to non-use of the battery when the determining device determines that the voltage of the discharging circuit has reached the reference voltage specific to the battery within the discharging time but after the time required to check the residual energy amount of the battery. And it is determined that the residual energy amount of the battery is insufficient when the determining device determines that the voltage of the discharging circuit has not reached the reference voltage specific to the battery within the discharging time.