1.377 inches is the actual dimension specified by SMPTE, or 34.975mm. The size was created by Dickson in collaboration with Eastman, and would have been in standard, not metric, units. An account of this is given in an article by Dickson in a 1933 SMPTE Journal. "Half Frame Cameras". Retrieved August 12, 2006. This size is also exactly half the width of the 2 3/4 inch-wide（69.85mm） "A-type" rollfilm which was the standard Eastman size at the time. 35mm is used in movies. "Enhancing the Illusion: The Process and Origins of Photography", George Eastman House. Retrieved August 12, 2006.
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1.377 inches is the actual dimension specified by SMPTE, or 34.975mm. The size was created by Dickson in collaboration with Eastman, and would have been in standard, not metric, units. An account of this is given in an article by Dickson in a 1933 SMPTE Journal. "Half Frame Cameras". Retrieved August 12, 2006. This size is also exactly half the width of the 2 3/4 inch-wide（69.85mm） "A-type" rollfilm which was the standard Eastman size at the time. 35mm is used in movies. "Enhancing the Illusion: The Process and Origins of Photography", George Eastman House. Retrieved August 12, 2006.
