And Hitchcock shot "Psycho" in 4-perf 35mm Academy, not Super-35, cropped to 1.85, so even a shorter diagonal.Īnyway, the tradition has always been a 50mm for FF35 as being "normal".įrom Wikipedia: "For still photography, a lens with a focal length about equal to the diagonal size of the film or sensor format is considered to be a normal lens" / "For a 35mm camera with a diagonal of 43 mm, the most commonly used normal lens is 50 mm, but focal lengths between about 40 and 58 mm are also considered normal. When you say "diagonal" though you have to remember that 4-perf Super-35 full aperture was only used in the Silent Era, and today Super-35 is cropped to 1.78, 1.85, or 2.40 so the diagonal is shorter. Acclaimed twentieth century directors like Hitchcock, Robert Bresson and Yasujiro Ozu were proponents of roughly this focal length, 50mm to be more precise, believing it to have the most natural field of view. According to SMPE, this gives us a normal focal length of 56mm. They reasoned that this would give a natural field of view to a cinema-goer sitting in the middle of the auditorium, halfway between screen and projector (the latter conventionally fitted with a lens twice the length of the camera’s normal lens).Ī Super-35 digital cinema sensor – in common with 35mm motion picture film – has a diagonal of about 28mm. SMPTE (the Society of Motion Picture and Television Engineers), or indeed SMPE as it was back then, decided almost a century ago that a normal lens for motion pictures should be one with a focal length equal to twice the image diagonal. So where between those extremes do you choose an angle that seems "natural"?Īccording to this the standard lens for 35mm is 50mm. But our area of sharp focus is only about 10 degrees or less. Peripheral vision extends out to about 140 degrees, which you can test by holding your arms out to the sides and while wiggling your fingers bringing your arms slowly forward until you notice the wiggling movement. The question of what focal length/format combination (or field of view) mimics human vision is a tricky business. But again whether a lens is deemed long or wide is a function of the format size, and the distance then determines the perspective. Most likely I think he was talking about the distortion or sense of depth, as in how a long lens can flatten perspective while a wide angle lens stretches things out and makes spaces seem larger than they are. It's possible he felt that looking through a viewfinder the magnification of a 50mm seemed to match what his other eye saw, but of course that depends on the magnification of the viewfinder optics too. It's curious that Hitchcock often mentioned 50mm as having a "natural" perspective that "gives you what your eye sees", but he shot on various formats including silent aperture, Academy and VistaVision, where a 50mm would give different angles of view.
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