For over 30 years the Kodak girl advertised Kodak cameras in the UK

The 'Speed Graphic' 4 x 5 inch plate camera dominated photojournalism in America during the 1930s. The Speed Graphic, first introduced in 1912, was manufactured by Graflex, a Rochester, New York based camera maker. The camera was a portable version of the studio view camera offering camera movements, interchangeable lenses and extendable bellows for extreme close-ups. Many models had coupled range finders for fast focusing as well as the traditional glass screen. Also fitted were open wire framed and optical viewfinders plus a large flashbulb holder. At this time Newspapers preferred their photographers to use plates as they could be processed individually, also the 5 inch format was very practical for newspaper layout as this sized negative exactly fitted 3 newspaper column widths. However the versatility of this camera had to be balanced against its weight and general clumsiness. 
 

Camera :  "Pre-Anniversary" Speed Graphic  Manufacturer : Graflex  Date : c1928 - 1939

Camera :  British copy of the American Speed Graphic. Manufacturer : MPP  Date : 1940

The Single Lens Reflex (SLR) designs comes from the 17th Century camera obscuras. It uses a mirror at an angle of 45 degrees to divert the image from the film plane to a viewing screen on the top of the camera. The SRL design was not necessary until the 1890's when the emulsion speed of dry plates made action photography possible. The SLR design enabled the photographer to view action right up to the moment the picture was taken.
In 1932 the German company Ihagee began production of the Exakta. It was smaller and more compact than previous SLR designs although it still used roll-film and a waist-high viewfinder. The camera was an immediate success.

Camera : Exakta A
Manufacturer : Ihagee
Date : 1932-c1940

In 1913 a German design engineer, Oskar Barnack, produced a prototype 35 mm camera. Barnack had poor health but was an avid hiker and amateur photographer. He wanted to take a smaller camera on his walks in the hills. In 1924 the camera went into production at the Leitz factory in Germany. It was called the Leica from the initials of  "LEItz CAmera" and took pictures the size of 24 x 36 mm. This was twice as large as the standard movie film picture (24 x 18 mm) and became the standard for 35 mm still photography. The capabilities of the Leica made a new form of photojournalism possible, as typified by the Magnum photographic agency.