The daguerreotype and the calotype processes were the foundations of photography.
The daguerreotype and the calotype are the foundations upon which the practice of photography is based. These two processes, the former developed in France, the latter invented by an Englishman, were the first methods by which images could be "fixed": A scene in the natural world could be transferred to metal or paper and become a permanent record. From these initial processes, photography went on to revolutionize how the world was seen.
Before the Daguerreotype and the Calotype
The concept of reproducing an image or scene from the natural world via material means had been sought by artists for some time before the invention of the daguerreotype and the calotype. The primary method that had been developed was the "camera obscura." This device, using angled mirrors within a box, allowed light to enter a box, over a tracing paper depiction of the scene desired, which was then angled via mirrors through a pinhole at the front. This image, though upside-down, retained the color and perspective of the original drawing and could be projected onto a wall or canvas. It was primarily used as an aid to painting.
The Daguerreotype
The daguerreotype was the first truly photographic process. It was invented by Louis Daguerre, a French artist and chemist, and was unveiled to the public in 1839. For many years Daguerre had been trying to fix images permanently and had worked with colleague Joseph Nicéphore Niépce in producing preliminary processes. The daguerreotype was the culmination of his efforts. The process was detailed and required great care. A silver-plated copper plate was polished so that there were absolutely no blemishes or marks upon it. It was then placed in a closed box over iodine in order to make it sensitive to light. Transferred into a lightproof box, the plate would be inserted into the camera where it would be exposed to light, capturing the desired scene. The image was developed using hot mercury and fixed by being immersed in a salt solution or sodium thiosulfate.
The Calotype
The calotype was introduced to the public two years after the daguerreotype, in England. Its inventor was William Henry Fox Talbot, a member of Parliament who was also a keen amateur artist. It was while sketching on holiday in Italy that Talbot began to conceive of a process to make drawing automatic, to capture the scene in front of him instantly. He used a camera obscura, but rather than simply project the image, he inserted a sheet of drawing paper coated in silver chloride. When it was exposed to light the image was fixed on the paper, but in reverse (much like film negatives today). He then placed this negative against a second piece of coated paper to produce the positive image.
The Difference Between the Two Processes
There are two primary differences between the processes. The first is the material onto which the image was fixed. Daguerre's use of metal plates, while his invention was revolutionary, was quickly deemed cumbersome, in no small part due to Talbot's use of paper to capture the image. The other difference is that the daguerreotype was a negative image that reflected a positive image while calotypes were negatives that could then be printed as positive images. The short time between these two important developments is evidence of how quickly photography evolved.
What Happened Next
Using the techniques devised by Daguerre and Talbot, inventors sought to push the process further. In America, ambrotypes used coated plates of glass to produce positive images, making it less expensive than the daguerreotype with its copper plates. The tintype used the same idea but with painted or lacquered iron sheets. However, it was not until the first flexible photographic films (and compact cameras) were developed by the Eastman Kodak company in 1885 that photography began to become a commonplace activity.
Tags: angled mirrors, camera obscura, daguerreotype calotype, exposed light, image fixed, natural world, positive image