George Pavlidis - Foundations of Photography: A Treatise on the Technical Aspects of Digital Photography

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Any study of photography naturally relates to the study of how one may use light (Greek originally pronounced , now simplified to fos) to write, inscribe, or create images (Greek pronounced ). fos + gives , the Greek word for to photograph. Light has had and continues to have a special impact on humans, in fact in everything that relates to what we perceive as life. It is what wakes us up in the morning, what warms us, and what gives us the images of the world around us. It has the power to turn a simple view at the sea into serenity and anticipation, the gaze at the forest into calmness, the glance at the sky and stars into cosmological and existential search, or the look at a loved one into joy.

Recognising the value of light in life, humans throughout history devised ways of capturing the images created by light, while, at the same time, wondering and exploring the very nature of this magical element, sometimes using science, sometimes using logic and philosophy, and sometimes relying on feeling and superstition. What is certain is that light is a key element of the universe that is our home, exists regardless of our perception of it, and even plays a defining role in relationships within the universe.

In science, many attempts have been made to explain the nature of light, which sometimes led to theories about the particle nature, the wave nature, or the electromagnetic nature of light. The first to support a particle theory of light was a brilliant person called Newton, when in 1675 he (but also other scientists of that era) argued that light was a continuous stream of particles travelling in a straight line from a source, thus, giving a pure particle character to light. Even in the same period but also later, several great scientific minds supported a wave theory of light, attributing to it exclusively a wave nature, like the waves on the water surface. Among them were Robert Hooke (1660), Christiaan Huygens (1678), Leonhard Euler (1746), Tomas Young (early 1800), Augustin-Jean Fresnel (1817), and Simeon Denis Poisson (1820s). With the development of electromagnetic theory, scientists such as Michael Faraday (1845), James Clerk Maxwell (1862, 1873), and Heinrich Hertz paved the way towards an electromagnetic theory of light. With the advent of Einsteins theory of special relativity in 1905, the idea of a dual nature of light was first introduced, which solved the paradox of the constant speed of light, creating, in this process, another paradox that space and time are somewhat more exotic parameters of the universe. At the same time, the light appeared to play an even more important role, since first appeared as the connecting element between energy and mass, through the famous Einstein simplified equation . In addition, the acceptance of the dual nature of light provided an elegant interpretation of the paradox of the photoelectric effect, the release of electrons from a surface when light falls upon it. In fact, it was this interpretation for which Einstein was awarded the Nobel Prize. This view was supported by scientists such as Max Planck (in 1900) with the interpretation of black body radiation, which reinforced a quantum theory of light (photons) that backed the dual nature while paving the way for the advent of quantum mechanics and quantum electrodynamics. Even to those not particularly fond of mathematics and science, the names of the aforementioned scientists sound particularly familiar and show the importance given by humans in the understanding of light, highlighting its uniqueness in the universe.

One might say that the study of light within subjects like photography is more related to its wave nature. As a wave, light corresponds to the known and mapped spectrum of electromagnetic radiation, since it is a carrier of energy in the universe. Apparently, the part of this spectrum that relates to photography is only a small one, the one called the visible spectrum, that is, those frequencies (or wavelengths) that are detected by the human eye. These frequencies are higher than microwaves, which are used in communication and some other technologies useful for heating, and are located between the areas defined by infrared and ultraviolet radiation. In addition, one of the characteristic properties of light that plays an important role in the study of issues related to photography is that of