(Germany): first 127 roll film SLR. Preliminary designs were on paper by June 1932. Took eight exposures of 4×6.5 cm (1⅝×2½ inch) nominal frames (40×62 mm actual frames) on 127 "Vest Pocket" roll film, and had a folding waist level finder and focal-plane shutter. The 1935 version was the first camera with a built-in flash synchronization socket (called Vacublitz) to automatically synchronize the recently invented flashbulb (first marketed as Vacublitz in 1929) with its shutter. The VP also established the oblong body shape and handling soon to be standard in 35 mm SLRs except that Exakta SLRs had primarily left-handed controls and were more trapezoidal shaped than rectangular. 1934 Eichapfel Noviflex (Germany): first 2¼ square format, medium format roll film SLR. Took twelve exposures of 6×6 cm (2¼×2¼ inch) frames on 120 roll film. Also had a fixed lens and focal-plane shutter. The 1937 version had interchangeable lenses. The square frame format precluded the awkward manipulations needed to take a vertical photograph with horizontal rectangular format SLRs having then standard waist-level viewfinders. The Noviflex was not commercially successful; it was the Franz Kochmann Reflex-Korelle (Germany) of 1935 that established the popularity of the 2¼ square format SLR. 1935 135 film, commonly called 35 mm film, introduced by Kodak (USA). Was (and is) 35 mm nominal width (1⅜ inch actual width), acetate base, double perforated film, pre-loaded into felt-lipped, daylight-loading cartridges ready-to-use for still cameras. Originally intended for Kodak Retina, Zeiss Ikon Contax and E. Leitz Leica 35 mm rangefinder cameras. Previously, bulk rolls of 35 mm motion picture film would need to be user cut and loaded, in complete darkness, into camera specific cartridges or magazines. The September 1936 release of Kodachrome (the first high speed [ISO 8 equivalent], realistic color film) in standardized 135 format (but not medium format roll film) spurred explosive growth in the popularity of all types of miniature format 35 mm cameras. The vast majority were not high-end SLRs or RFs, but basic amateur RFs such as the nearly three million selling Argus C3 (USA) of 1939. Originally, each US$3.50 (including processing) Kodachrome cartridge gave eighteen exposures if the camera used the 24×36 mm frame size (double the frame size of 35 mm cine cameras) established by the Multi-Speed Shutter Co. Simplex (USA) camera of 1914 and popularized by the E. Leitz Leica A (Germany) of 1925. The 24×36 mm frame size did not become