Photography, with its stark veracity and meticulous detail, has collectively become a synonym for truth and reality. And today, photographic reality, in all of its media manifestations, dominates most of our waking hours. We give photography a level of verisimilitude that few other communication media enjoy. Yet what we see with our eyes and what the camera sees are actually quite different.
Our retinas at the back of our eyes and the digital sensors at the rear of our cameras and cell phones perform similar functions, but see the world in different ways. The surface area of both retinas and high-quality 35mm cameras are about the same, yet most of the retina is composed of rods, optical sensors that see mostly black and white and detect movement. Rods supply an important peripheral vision component to sight; something that protects us from an impending attack from a predatory creature. The center of the eye is known as the macula, an area about the size of a dime. This small area contains most of the cones, the sensors responsible for seeing color and detail. The macula and its concentrated center, the fovea, are the heart of our sight.
The sensor in all digital cameras is much more egalitarian with all pixels given equal light-capturing capabilities. The camera’s field of view is only limited by how wide a lens is attached to it. The eye, on the other hand, has a natural tunnel vision, something like a bird of prey.
But our eyes never stay in one place. They are constantly moving, taking dozens of "pictures" every second. These images are instantly sent to the brain where they are stitched together creating a composite image of what we see. The camera, on the other hand, is a "one and done" device. Unlike the eye, there is a shutter that opens for a short period of time and then closes. Even film and video have shutters; only they operate sequentially at rapid speed. Generally speaking, where the eye stitches together many images to create vision, the camera does it with one take. When we say we see the whole room when we walk into a space, what we are actually seeing is a sequence of images put together in our brain.
The human eye and digital sensors differ in another significant way: dynamic range. The eye has the ability to see detail in almost the darkest shadows and the brightest highlights. That range of vision from light to dark is called dynamic range. In photography we measure that light to dark range in "stops," which is 2n. One stop of brightness is twice as bright, two stops is four times, etc. The human eye has a 20 stop dynamic range. That means you can see over one million shades of gray. The best digital camera has a dynamic range of 14 stops or about 16,000 shades of gray. When we walk into a dimly lit room, our eyes can see both the room and the view out the window without a lot of strain. Both digital sensors and film, however, cannot resolve detail in this circumstance.
You may have heard the term HDR: high-dynamic-range. It’s a way of extending the camera’s visual range by layering a range of exposures of the same shot. This is one effective photographic technique when both the camera and the subject are not moving. However it’s not the only available technique at our disposal.
As architectural photographers, in these situations we can add light to compensate for the dynamic range difference. In daylight, we add electronic flash. At dusk and in nighttime situations we add either tungsten or LED illumination to open shadows and light dark surfaces. We use a variety of light modifiers that soften shadows and create "window light" effects that our brain understands and likes. We also light in a way not to overpower existing light sources, but enhance their illuminating properties.
At the end of the day, a skilled photographer can create an image that closely replicates how our brains conflate images from the information received from the retina in fractions of a second. All photography is a clever re-creation of how we actually see. Our eyes are wonderful tools and cameras are just crude tools used to replicate what we actually see.