The 35 millimeter camera also known as the “candid” camera was developed by Oskar Barnack. In 1905 Oskar Barnack had the idea of reducing the format of the negatives and then enlarging the photographs after they had been through the exposure. Oskar was the development manager at Leica where he was able to test his theory and put it into practice. The world’s first 35 millimeter camera was produced by Oskar taking an instrument for taking exposure samples for cinema film and turning it into the “Ur Leica”. This was creater by Oskar Barnack in 1912 to 1913. In the 35 millimeter the supply and take-up spools were 25 mm in diameter and the shutter used was a cloth roller blind type. Oskar intended this invention to be used for his own personal use. The invention grabbed the attention of Ernst Leitz Jr. and he tried contacting Oskar in 1914 to try and patent the product. Ernst was unsuccessful because Oskar Barnack stayed true to his word when he said it was strictly for his personal use. With his small prototype of a camera Oskar had begun documenting events in his hometown in 1914. Oskar’s success with the first Leica camera continued on throughout the years where he became more successful from the invention of more cameras. Leica A cameras went on sale in 1925 where photographers were the ones to buy the cameras and make ‘quick use’ of them. In 1932 there were already 90,000 of the Leica cameras being used.
http://inventors.about.com/library/inventors/bl35.htm
http://www.answers.com/topic/ur-leica
http://us.leica-camera.com/culture/history/leica_products/