In a first exposure condition calculating operation, proper exposure conditions in imaging are calculated by the imaging element including the effective exposure time and ISO sensitivity without preliminary light emission from the strobo part. In a second exposure condition calculating operation, the exposure condition is determined by compensating at least the ISO sensitivity among the exposure conditions calculated in the first exposure condition calculating operation by dimmer or light control operation with preliminary light emission of the strobo part. Exposure of the imaging element is executed as a regular imaging operation under the exposure condition calculated and determined in the second exposure condition calculating operation.