Excuse me each great god, and a little don't understand, the Canon camera with Dcraw get Raw format into tiff program in matlab, the aperture of the camera shutter focal length white balance must be, different distance shooting objects, why drive value changed? The original data of the camera is not the response value of CCD and CMOS? Should be associated with illumination, intensity of illumination is not affected by the distance? (I used the camera to Canon 5 d mark III)