Some basics. I like the “toothpaste” analogy, it makes it easy to visualize. Something he doesn’t cover that many of the folks that are just getting into DSLR’s for video don’t understand is how sensor size affects DOF as well. Many newcomers don’t understand that all other variables being equal, a 5D is going to give you a shallower DOF versus a 7D. That’s some of the reason Philip Bloom has pre-ordered a new full frame 5D mklll for video even though he has already purchased a Canon C300. Mitch Gross from AbelCine covers some of the sensor size/lens variables in another great video here.