Burning Questions: WTF is a Petzval Lens?

Photographers and Cinematographers are enamored with creative ways to separate their subjects from their backgrounds. One such trick is to implement a "swirly" background effect that turns otherwise mundane scenes into something out of a dream. Although the swirly bokeh effect may be getting lots of hype these days, it's far from a new advancement in photography; we can all thank Hungarian mathematician Joseph Petzval for this creative and game-changing effect.