17.5 mm film
film gauge
17.5 mm film was a film gauge for as many of eight types of motion picture film stock, generally created by splitting unperforated 35 mm film.
History
17.5 mm film was first documented in 1898 with the creation of the Birtac camera, and subsequently went through several different iterations up until the end of World War II, when Kodak's 16 mm film and 8 mm film largely took its place in terms of popularity. In addition to original pioneering experiments, 17.5 mm film was used during World War II to use existing 35 mm stock more economically. Afterward, this format continued to be used primarily in developing countries such as India, or for projects where usage of regular 35 mm film would have been too expensive.
Partial list
Birtac
The British-American photographer and inventor Birt Acres split 35 mm film in half for his Birtac camera-projector in 1898. The film used had a single row of perforations running down the left side of the image, with two perforations per image. Historically, this is considered to be the first piece of motion picture equipment that utilized 17.5 film.
Biokam
Alfred Wrench and Alfred Darling created second 17.5 mm format film in 1899 in London. The only differences between their and Acres' film was that their film had central perforations, and it could be utilized as a medium for still pictures as well. The Biokam camera, projector, and printer (all in one machine) was produced by the Warwick Trading Company.
“17.5 mm film” enters the record as film gauge. Crown Archives preserves that source wording while asking what film and gauge can confirm, complicate or overturn.
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“17.5 mm film” is worth following because a concise public description often conceals a longer documentary argument. Here, film and gauge provides the most credible route into that argument.
Attribution, date and provenance are strongest when supported by the original work, a catalogue record and documented transmission. The source revision retrieved here is dated Jan 18, 2025. The linked authority identifier is Q3072028. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1898 and 1899.
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This entry incorporates text from “17.5 mm film” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.