A Petzval lens is a historic photographic lens created by Joseph Petzval in 1840, known for its distinctive swirly background/bokeh effect. It revolutionized portrait photography with its ability to capture sharp images with shorter exposure times. The lens design features a sharp focus in the center, softening towards the edges, ideal for portraits. Despite its 19th-century origins, the Petzval lens's unique optical qualities maintain its popularity among modern photographers and videographers.