Marc Levoy, a former Stanford University Professor and now an Engineer at Google, has put his entire digital photography course online for free, where you can learn about the history, scientific theory and real-world practice of photography. The 18-lecture course, which comes with videos and a range of other materials including applets demonstrating photographic principles and information on course assignments can be accessed for free at: https://sites.google.com/site/marclevoylectures/home.