There's no definitive answer to this question, as the best shutter speed for photographing the Milky Way will vary depending on a number of factors, including the camera you're using, the lens you're using, the ISO setting you're using, and the amount of light pollution in your location. However, as a general rule of thumb, a shutter speed of 30 seconds should be used when photographing the milky way with a DSLR camera and a wide-angle lens.