The Petzval is a unique lens with a design dating back to the origins of photography itself. This lens was created to bring that old large-format lens design into the world of DSLRs. It features individual aperture plates ranging from 2.2-f/16, manual geared rack focus (focus achieved by knob), and an attached hood. Three of the aperture plates feature unique shapes: star, teardrop, and hexagon, which are rendered in images as bokeh. All other aperture plates are circular. Bokeh for this lens in general can have a unique swirling effect under the right conditions.