A camera system is provided. The camera system includes an image sensor, at least one light source, and a processing unit. The image sensor is configured to capture a plurality of images. The processing unit is configured to perform the following instructions. A plurality of reflection values on at least one subject in the captured images is acquired. A relationship between a luminance level of the light sources and a reflection level on the at least one subject is obtained. A luminance configuration is determined according to the relationship between the luminance level of the light sources and the reflection level on the at least one subject. A luminous power of at least one of the light sources is adjusted according to the luminance configuration.