1. Before Photography Part 1: Discovering Light The most basic aspect of photography is our understanding of how light works, and the first known writings on this come from well over two thousand years ago in China. Mo Ti (later known as Mo Tsu) was a philosopher who lived from 470 to 391 BC. Unlike most philosophers he came from a poor background, perhaps why his teachings were based on the conviction that all men were of equal worth. His followers or 'Moists' were taught that right living demanded they take responsibility for the well being of others and ensured that their actions did not harm others, but practised a universal love for others. If people follow this path, the world is 'ordered and peaceful,' if not, 'the world becomes disorder, violent, and chaotic.' Although difficult to argue against, these ideas did not generally win the affection of the rich and powerful, and Moism soon died out. Mo Ti also thought deeply about the natures of shadows, realising that they were formed by light travelling in straight lines, the first recorded law of optics. He also was able to use this to explain why the images formed when light entered a darkened room through a small aperture were inverted, so can be credited both with recognising the role of an aperture in forming an image and also with an understanding of what later became known as the 'camera obscura' which will be looked at in more detail in a later section. Back in the more primitive west, the Greek philosophers were also noticing similar effects. Aristotle, around 330BC, wondered how the sun, shining through a square hole into a darkened room, could create a circular image, but it was a problem for which he had no solution. He did however note that decreasing the size of the aperture in viewing an image created a sharper image. Euclid (around 325-265BC) in Alexandria setting out his 'Geometry', clearly understood that light travelled in straight lines, and he also wrote a treatise on 'Optics' which discussed among other aspects ideas about binocular vision. Two copies of this work survived and when it translated and published with notes in 1573, Egnacio Danti added his description of the camera obscura to show how Euclid had arrived at his conclusions. Heron of Alexandria produced his 'De Speculis' and 'Caoptrica' around 125 AD. His is the oldest surviving Greek work on mirrors - plane, convex and concave and he also stated the law that the angle of incidence is equal to the angle of reflection. A few years later, around 150 AD, Ptolemy, also from Alexandria, wrote his 'Optics' extending the work of Heron and Euclid. Ptolemy was the first to write about refraction, perhaps because clear glass was now available. Part 2: Ways of Seeing Light itself and how we see objects was also a problem that attracted the Greeks. Empedocles (483-424 BC) thought of light as matter, small particles emitted by objects that travelled to reach our eyes. When we think of light as photons we are using a model similar to his. Others such as Herodotus (484-425 BC) and later Aristotle (384-322 BC) also argued that objects were visible and had the properties we perceived because they emitted light that is detected by our eyes, although they did not see light as matter, but rather as an 'emanation', something given off by substances. We might regard this in more modern terms as light waves, although the wave theory of light dates from the work of the Dutch mathematician and physicist Christiaan Huygens, (1629 - 1692). Plato (428-347 BC) also speculated about the nature of seeing, thinking of it in terms of a reaching out from the eyes of the viewer to discover the subject. It was a view modelled on the idea of touching, although making use of an invisible agent. Of course we now think scientifically in terms of rays of light radiating from objects in straight lines in all directions, some of which enter into our eyes to form a retinal image, producing sight. However true this may be in physical terms, Plato's model is firmly embedded in our language and ways of thought. We think of seeing as a kind of touching, essentially a tactile act, concerned with textures. Looking at something is an active process. We seldom think in terms of the rays from objects making themselves seen by us. This tactile metaphor of seeing applies even more to the act of photography than of sight. Taking a photograph - especially a still photograph - is seen very much as an active proves in which we reach out and grab our copy of the scene we have framed in our viewfinder. We feel it that way, and so do people that we photograph. Whether we are photographing people who fear we are stealing their souls or urban dwellers who think we are invading their privacy, our act of photographing is at times resented as an intrusion. Video cameras are somehow less intrusive, perhaps seen more as a passive device, one that receives signals, into which the images flow. Filming lacks the kind of deliberate selection and isolation implied when we frame the image and press the button. On numerous occasions I've seen people treat still photographers with suspicion and even rage while ignoring the video cameras recording them. The first description comparing the working of the eye to a camera came from the great Abou Ali Al Hassan Ibn Al Haitham, born in Basra on the Persian Gulf, in 965 AD. Better known under his Latinised name of Alhazen, he worked in Alexandria from around 1015 to 1021 on his great treatise on optics. It was his work, translated into Latin around 1270, which brought this knowledge to Western Europe. Part 3: Lenses Some natural quartzite and other transparent crystals can be shaped to act as convex lenses. One of the first to be found in archaeological excavations was discovered by Sir Austen Henry Layard in his excavations in Babylon in 1850, and was dated from around 900BC. However many consider - particularly because of its facets - that its purpose was decorative rather than useful. More recently, Robert Temple found many examples of similar early crystal lenses in museum collections around the world, which are usually not acknowledged as such. He thinks the Layard 'lens' is a damaged example of a lens. His book 'The Crystal Sun', posited that an advanced optical technology was widespread across the ancient world. As well as convex lenses similar to the Layard lens he also found concave lenses and some showing the use of complex 'toroidal' grinding techniques to correct eyesight for astigmatism. His controversial book suggests that as well as spectacles and other similar uses, the ancients also made telescopes and microscopes. One part of the evidence for his theory is the existence of many designs on early artefacts which are too small and intricate to be seen or made with the naked eye. The cover of his book shows a Greek drawing which could be of a man looking through a telescope. Perhaps if he had written this work before his work speculating on alien visitors from Sirius it would have received more careful academic consideration. One of his more interesting speculations concerns Archimedes (287-212 BC), who wrote of the use of a large burning glass as a weapon to set fire to ships in an opposing fleet. Temple claims that this may actually have been used - an early example of true 'Star Wars' technology. Whatever opinion may be formed of some of his more fanciful suggestions in this and other books, it does seem likely that lenses were rather more common than had previously been though in the ancient world, and were probably in use in Egypt from around 2500BC. Glass was probably first made in the Middle East, between the Rivers Tigris and Euphrates - now Iraq - around 2500 BC. Early glass was not clear and it was only around 100BC that the Romans managed to produce a clear material. With the fall of the Roman Empire, many of their secrets - including some of their glass making skills - were preserved in Egypt and Syria. However it was not until the discoveries of Venetian glassmakers from around 1200AD that clear glass again became available again in the West. Lenses for eyeglasses (spectacle lenses) began to be mass-produced in Venice in about l275. Among those in England who studied the work of Alhazen, following its translation into Latin around 1270, were Robert Grosseteste (1168-1253), the Chancellor of Oxford University who made use of plano-convex lenses, and Roger Bacon (1214-1294). Grosseteste carried out optical experiments and Bacon published his famous works on optics and other subjects. Their work marks the beginning of the scientific study of optics in Western Europe. From somewhere around this date, lenses were commonly used in camera obscura, allowing a brighter image and a sharper picture. The disadvantage is that the aperture to screen distance had to be precisely matched to the power of the lens and also to the distance of the object from the lens. In room size camera obscura this normally meant using a moveable screen. The original camera obscura - what we might now call a pinhole camera - required no focussing, although the aperture diameter for optimum sharpness is highly dependent on the aperture to screen distance. Making the aperture larger than optimum gives a brighter but less sharp image. That a smaller aperture could also make the image less sharp could only be explained by the wave theory put forward later by Huygens, but early camera obscuras mainly used apertures well above the optimum size.