1. An image capturing system, comprising: a first image capturing module, having a first lens, a first aperture and a first image sensor, wherein the first lens is used for imaging the scene to the first image sensor, the first aperture is used to limit the amount of light with a first optical-wavelength range, the first image sensor has a first optical-wavelength detection range, the first image capturing module is used to generate a first image corresponding to the first optical-wavelength range; a second image capturing module, having a second lens, a second aperture, a third aperture and a second image sensor, wherein the second lens is used for imaging the scene to the second image sensor, the second aperture is used to limit the amount of light with the first optical-wavelength range, the third aperture is used to limit the amount of light with a second optical-wavelength range, the second image sensor has the first optical-wavelength detection range and a second optical-wavelength detection range, the second image capturing module is used to generate a second image corresponding to the first optical-wavelength range and a third image corresponding to the second optical-wavelength range, there is a distance between the optical axis of the second image capturing module and the optical axis of the first image capturing module; and a depth map processing/generating device, generating a first depth map according to the parallax of the scene observed in the first image and the second image, and generating a second depth map according to the difference/ratio of sharpness/blur between the second image and the third image.