In 1886 George Eastman and Franklin M. Cossitt received the patent for their Eastman Detective camera, a box camera for paper roll film. The roll-holder was an Eastman-Walker rollholder, patented in 1885. It could be replaced by a plate holder. The camera had a pivoted drop-shutter with adjustable falling rapidity and a focusable symmetrical lens with four elements in two groups. The drop-shutter was an alternate construction to focal-plane shutters, a kind of near-focal-plane shutter.
- Patent at Google patent search