| 摘要 |
PROBLEM TO BE SOLVED: To inform a user of the exchanging or charging time of a power source battery for every photographing lens by deciding the reference voltage of the power source battery in accordance with information concerning the load torque of a driving part for driving a photographing optical system in a mounted lens barrel. SOLUTION: The load torque information of a lens driving system for driving a focusing lens group is stored in a storage circuit 45. A decision circuit 42 decides a battery check voltage based on the load torque information stored in the circuit 45 of mounted photographing lenses 30, 30-1, 30-2,... and a reference value, a low level value and a high level value stored in a storage circuit 44 and outputs it to a discrimination circuit 43. Then, the circuit 43 compares the power source voltage with the battery check voltage and outputs warning display on an LCD 24 when it is necessary to exchange or charge a power source battery 15. Thus, the accurate battery check warning display can be realized and the energy of the power source battery is efficiently and effectively utilized.
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