Cameras work in mysterious ways. That’s even more true in the digital era, but the simple mechanics of a shutter are about as astounding to me as the workings of a fine watch or NASA’s ability to put a man on the moon. Once you get beyond the basics I’m not much of a mechanical engineer. That’s why this video post from DIY Photography is especially appealing. It explains in easy to understand terms how a camera’s shutter curtain works, and how a flash synchronizes with the shutter. I’m particularly fond of the shower curtain analogy: close from one side, then open from another. That’s kind of the same way a shutter curtain, actually a pair of curtains, works. The video is sure to help many photographers figure out how their SLRs functions—and that almost always leads to better pictures. Why? Because with an understanding of how a camera works, we can make better technical choices to achieve the specific camera and lighting effects we’re after. And we’re more apt not to mess up shutter sync when working with a flash.