Photography, according to the Merriam-Webster dictionary, is “the art or process of producing images by the action of radiant energy and especially light on a sensitive surface (such as film or an optical sensor.)” Since photography is an invention, the word was also created by combining the Greek roots φωτός (phōtos) or "light" and γραφή (graphé) "drawing.” Thus, photography is "drawing with light.”
Drawing with light requires two structural elements: radiant energy and matter. In the book of Genesis (Beginnings), the Bible describes the formation of the earth with this insight clearly in mind.
1 In the beginning God created the heavens and the earth. 2 Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters. 3 And God said, “Let there be light,” and there was light. 4 God saw that the light was good, and he separated the light from the darkness. 5 God called the light “day,” and the darkness he called “night.” And there was evening, and there was morning—the first day. (NIV, Genesis 1:1-5).
In the Genesis narrative, light relates to God’s creation of the universe, of which the sun and other stars were foundational. Light is also of great scientific interest. A star, again according to Merriam-Webster, is “a self-luminous gaseous spheroidal celestial body of great mass which produces energy by means of nuclear fusion reactions.” This energy strikes earth both as energy waves and particles or photons. The energy waves vary by frequency, and the part our own eye sensor can detect is called visible light. On the Pink Floyd album cover The Dark Side of the Moon, for example, a beam of light passes through one side of a glass triangle and is dispersed on the other side into different colors, a graphic illustration of how different frequencies produce different colors depending their length. Shorter wavelengths were blue and longer ones were red.
The second element that remains to be examined is matter. Initially the earth was “formless and empty,” according to the Bible. Science, for its part, defines matter as a “material substance that occupies space, has mass, and is composed predominantly of atoms consisting of protons, neutrons, and electrons, that constitutes the observable universe, and that is interconvertible with energy.” Photography captures and records this complex interaction of energy (light) and matter, itself composed of atoms.
A permanent way to capture light’s impact on matter eluded us for thousands of years. It was not until the mid-1800s that our understanding of chemistry and optics was sufficient to invent ways to record light striking matter. Early images were crude by modern standards, but they ushered in a new era of transporting captured images of events and people thorough time and space. By the late 1900s, scientific, technological, and commercial advances fostered a shift in the “sensitive surface” from film (chemistry-based) to solid-state image sensors (electronic). This lowered the cost and difficulty of taking pictures, exponentially increasing the world’s supply of recorded images, for which demand has always been high.
The development of the sensor used to capture the light is itself a fascinating technological achievement. Of interest here is the Bayer filter that replaces the traditional chemical-based film with a digital chip arranged in a checkerboard type of pattern of red, green, and blue sensors or pixels. This chip captures incoming light arriving through the camera lens, measuring the light’s intensity and color as it falls on the pixels. These values are then interpolated mathematically to arrive at a very accurate representation of the actual image. Thus, the sensor is not an exact replica of reality, but represents a simplified reproduction of the true image. This has always made me ponder the reality behind the shadows as told in the story of Plato’s Cave. There is more, of course, to the capturing of an image. These include the aperture (opening) of the lens, the length of time the shutter is open, and the sensitivity of the sensor to capturing light (amplification).
The main point to be made here is that although there is a scientific and technical aspect to light drawing, it is nonetheless a highly subjective process that includes many assumptions and decisions on what to emphasize and what not to emphasize. This aspect of photography is more the art—expressing the image maker’s purpose. Common goals include emotional impact, creativity, composition, technique, and story-telling. Images that have captured our attention therefore make effective use of the available technology at the time, but also tell a story in a way that leads to deeper emotional engagement with the subject matter.