Every camera has light leaks, the world is not perfect. The question to ask, is what affect the almost unmeasurable amount of light leaking in has on images. With a film body, and the back door opening and closing, it was really critical to reduce light leaks to a almost zero amount, because any light leaking in was exposing your film, for days, weeks, months, or longer. With digital, its only the time of exposure that counts, not when you have a lens cap on, or are setting exposure before you open the shutter.