though usable at a larger 120 x 180 cm (ten times larger) on a billboard to be viewed no closer than 5 metres. Since the inverse square law applies to illumination intensity at increasing distance, enlargement beyond a certain size becomes impractical, requiring extended exposure times and dependent on the extent to which dampening of enlarger supports may eliminate vibration causing blur in the resulting print. Biggest enlargement The claim for the biggest analogue enlargement ever made from a 35mm photograph is that for Ernst Haas' wildlife picture taken in Kenya in 1970. It required a 5-hour exposure using the Kodak Colorama process, for a giant transparency. The 508-times enlargement consisted of 20 vertical panels of 3 feet width and 18 feet height (91.4 x 548.6 cm) for a total size of 18 x 60 feet (5.48 m x 18.28 m). Displayed at Grand Central Station in New York in 1977, it was Illuminated from behind with 61,000 watts of light; it was the first time a 35 mm picture had been used for an ongoing series of Kodak advertising displays there c.1950–1990. The transparency print was destroyed after exhibition. Manufacturers As the photographic market shifts away from film-based towards electronic imaging technology, many manufacturers no longer make enlargers for the professional photographer. Durst, which made high quality enlargers, stopped producing them in 2005, but still supports already sold models. Manufacturers old and new include: Agfa Beseler Bogen De Vere Durst Dunco enLARGE Fuji Gnome Photographic Products Kaiser Fototechnik Kienzle Phototechnik Kindermann Klatt Leitz Liesegang Linhof LPL Lucky (now owned by Kenko) Meopta Omega Ōmiya Shashin-yōhin K.K. Paul Teufel & Cie Photogerätebau Polskie Zakłady Optyczne Sun Ray Photo Company See also Contact printer for a non-enlarging method of producing photographic prints; Gelatin silver process for an overview of the dominant photographic printmaking process; Image projector for a directory of projector types; Overhead projector for another use of a similar design, for display; Epidiascope for a design that could project images of opaque originals; Photographic printing for an overview of analogue photographic printmaking methods. Notes References Photography equipment