and imaging lenses of the twin lens cameras (first production 1882 [Marion Academy; UK]; not necessarily twin-lens reflex [TLR] camera, invented 1880 [one-of-a-kind Whipple-Beck camera; UK]) popular in the 1880s and 90s. 1891 Bram Loman Reflex Camera (Netherlands): first focal-plane shutter SLR. Had mirror rise synchronized with the release of a roller blind shutter, with speeds from ½ to 1/250 second, internally mounted in front of the focal plane, instead of the previously normal unsynchronized, external accessory in front of the lens. An internal camera-mounted traveling-slit FP shutter's main advantage over the competing interlens leaf shutter was the ability to use a very narrow slit to offer up to an action-stopping 1/1000 second shutter speed at a time when leaf shutters topped out at 1/250 sec. – although the available contemporaneous ISO 1 to 3 equivalent speed emulsions limited the opportunities to use the high speeds. Early 20th century 1903 Folmer & Schwing Stereo Graflex (USA): first (and only) stereo SLR. Strictly speaking, the Stereo Graflex was not a "single"-lens reflex camera, because, as a stereo camera, it had two imaging lenses. However, it had a reflex mirror and a typical for the era leather "chimney"-hooded waist level finder, albeit with dual eyepiece magnifiers. It took 5×7-inch glass dry plates. 1907 Folmer & Schwing Graflex No. 1A (USA): first medium format roll film SLR. Took eight exposures of 2½×4½ inch frames on 116 roll film. Had folding waist level finder and focal-plane shutter. A sister SLR camera, the Graflex No. 3A, was released at about the same time. It took six 3¼×5½ inch "postcard" frames on 122 roll film. Roll film (usually 120 type) SLRs became the dominant SLR type in the 1930s. The various models of large and medium format Graflex SLRs made beginning in 1898, and culminating in the 4×5 inch sheet film Graflex Super D of 1948, are the best and most famous American-made SLRs, if only for the shortage of competition. Graflex quit the camera business in 1973. A-127 is the rarest and most valuable at 1254 dollars – 3400 dollars 1925 Ernemann (merged into Zeiss Ikon, 1926) Ermanox Reflex (Germany): first SLR with high speed lens (10.5 cm f/1.8 or 85mm f/1.8 Ernostar). Established SLR as viable photojournalist's available-light camera. Had folding waist level finder and focal-plane shutter. Used 4.5×6 cm glass plates or sheet film; adaptable to roll film. 1930s 1933 Ihagee VP Exakta