Thermal fields are usually obtained by infrared camera (operating in 3-12 mu m). However, the infrared cameras are expensive, fragile and low resolution, thus the infrared camera is more used for laboratory researches. Nowadays, silicon based sensor camera has been widely used to perform real-time observation of the kinematic fields, mainly thanks to digital image correlation or interferometry. Silicon-based camera is also sensitive in the near infrared spectral ranges (operating in 0.7-1.1 mu m). An automatic prediction of the camera exposure time is developed and presented in this paper to follow the surface emissivity of the sample and avoid saturation of the gray level.