To reduce weight and space camera manufacturers devised alternative ways of carrying plates and film in cameras and in accessories to fit existing cameras.
B20) was a block form double slide where one long piece of film was wrapped around a central partition, it was loaded from the bottom edge of the slide. This was not the case however; the uptake of celluloid was by no means immediate and probably did not overtake the use of glass with the serious amateur until the mid 1900s, it did though encourage many more people to take-up photography. There were several reasons for this: early celluloid films had a reputation for cockling producing slightly uneven sharpness; their speed deteriorated more quickly than plates and curling during development was a problem. This section looks at film and plate holders as accessories or attachments rather than integral changing mechanisms within cameras and concentrates on apparatus available in Britain. From the outset of photography ways have been sort to lighten the load of the photographer. A trough was often present at the bottom of the slide into which any excess liquid on the plate could drain.