The camera obscura is an optical device thatprojects an image of its surroundings on a screenor wall. It is used in drawing and was one of theinventions that led to photography and thecamera. The device is made up of a box or roomwith a hole in one side. Light from an externalscene passes through the hole and strikes asurface inside where it is reproduced, upside-down, but with colour and perspectivepreserved. The image can be projected onto paper,and can then be traced to produce a highlyaccurate representation. 470 to 390 BCE
history of photography commenced with the invention and developmentof the camera and the creation of permanent images produced in 1826 bythe French inventor Joseph Nicéphore Niépce. To make this he used acamera obscura. He dissolved a silver coin in acid the painted it onto apiece of paper, he put this in his camera and left it for 8 hours.
• The daguerreotype was the first commercially successful photographic process. The image is a direct positive made in the camera on a silvered copper plate. The raw material for plates was called Sheffield plate, plating by fusion or cold-rolled cladding and was a standard hardware item produced by heating and rolling silver foil in contact with a copper support. The surface of a daguerreotype is like a mirror, with the image made directly on the silvered surface, it is very fragile and can be rubbed off with a finger, and the finished plate has to be angled so as to reflect some dark surface in order to view the image properly. Depending on the angle viewed, and the colour of the surface reflected into it, the image can change from a positive to a negative.
Cyanotype is a photographic printingprocess that gives a cyan-blue print. Theprocess was popular in engineeringcircles well into the 20th century. Thesimple and low-cost process enabled themto produce large-scale copies of theirwork, referred to as blueprints. Twochemicals are used in the process:Ammonium iron(III) citrate andPotassium ferricyanide.Sir John Herschel discovered thisprocedure in 1842.
• William invent the collotype process, the first photographic negative• He invented this in 1835.