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Difference between EI and ASA/ISO?
Connor Adam posted a topic in Film Stocks & ProcessingHey, I was reading through Kodak's 'The Essential Reference Guide for Filmmakers' and came across the following: A word about film speeds You probably know that motion picture films use exposure index (EI) to indicate speed. Although similar, EI is not the same as the ASA or ISO speed used for still films. EI denotes a somewhat conservative figure related to the higher quality requirements of motion picture film that must be projected onto a large screen. Typically the EI speed is about one stop lower than ASA or ISO. EI 500 film, therefore, is the equivalent of ASA/ISO 1000. Is anyone able to develop further on this? It is the first time I've come across the concept that EI is not the same as ISO. If I take what is written literally, does this mean that I should be setting my light meter to read at 500 instead of 250 (assuming I am shooting on say 250D stock) to get correct exposure? All the best, Connor