Issued in 1973, this Austrian commemorative stamp honors the Europhot Congress held in Vienna and celebrates Josef Petzval (1807–1891), the pioneering mathematician and physicist known for designing the first portrait photographic lens. The design showcases a beautifully rendered Petzval brass lens against a clean blue background, highlighting Austria’s contributions to early photographic technology. Printed with crisp detail and strong contrast, the issue is prized by collectors of photography-themed stamps. A notable piece for both thematic and Austrian philately.