Plate Cameras are really defined by the type of film they originally used rather than the actual attributes of the camera 's construction itself. 'Plate' refers to the sensitized photographic sheet used to take the image. The earliest plate cameras used metal plates as in the Daguerreotype and Ferrotype positive processes, but later glass plate negatives became the norm, these are the more commonly found and are what we will deal with here. Early glass plates were pre coated in albumen, to allow the photographic emulsion to form an even smooth coating over the surface, as with films of today, they had to be handled in complete darkness. Below are two original boxes of plates.

Plates were identified by sizes, referring to the size of the sheet, not the image area, as below.

Identity	Size (inches)	Size (cm)
Whole Plate	6.5 x 8.5	16.5 x 21.5
Half Plate	4.25 x 5.5	11 x 14
Quarter Plate	3.25 x 4.25	8 x 11
Sixth Plate	2.75 x 3.25	7 x 8
Ninth Plate	2 x 2.5	5 x 6
Sixteenth Plate	1.375 x 1.625	3.5 x 4