Your eye and your camera "see" differently. The eye
roams around and focuses on many points within its field of view—it is
constantly active and any peripheral vision limitations are compensated for by
a simple turn of the neck. The camera only “sees” in rectangular frames, and
focus is fixed on one plane, modified by the depth of field you set via
aperture choices. Its peripheral vision is determined by the focal length you
choose when using the zoom, or with primes (fixed focal length lenses), by the
focal length of that lens.
The top photo was made with "default" or factory settings of the camera. While fairly true to the cast of light on that day, it lacks the "punch" of rich colors created by choosing a "saturated" picture control. Knowing how you want to interpret a scene points you in the direction of making certain settings that will communicate the emotional qualities of the scene you want to express and bring the image more into line with how your mind interprets it.
The colors you record depend upon the prevailing cast of the
light under which you photograph, and how you set the color balance
accordingly. The eye adapts and constantly balances color, regardless of the source
of illumination. For example, a white shirt will be seen as white regardless of
the color cast (unless it is very strong), even under artificial light. If you
do not adjust color balance (known as white balance) in your camera under, say,
incandescent light, it will record as much warmer than the eye sees.
The eye dilates and constricts to adjust for changes in
brightness, and while color reception is lessened in low light, that adjustment
is automatic. When photographing, we must adjust the ISO according to the light
level. That’s because at the moment of exposure the aperture and shutter speed
settings record the energy of the light
in one fixed pulse.
In short, the eye/mind is both receptor and active
participant in perception, while the sensor in a digital cameras reacts to and
records light according to set rules of exposure and sensitivity.
The difference between these two exposures is in white balance settings. The top image was made using "daylight" white balance and one below is made on "tungsten" white balance. Recognizing color casts and changing them to match what the eye sees (top) and what the camera records is an important aspect of aligning what the eye and the camera sees.
The above may seem obvious, but one of the factors in making
images with a camera is that we cannot presume that the sensor will respond to
what we see in the viewfinder, regardless of the circumstances or lighting
conditions. Understanding how the two differ in their response to light, and
how we can modify camera functions to make them more in tune with what the mind
perceives (and interprets) is one of the most important, and perhaps least
understood and appreciated aspects of photography.
The eye (and by that I mean the mind and eye combination) is
an amazing instrument that continually sends messages to the brain, where they
are woven with other impulses to form images, the codes that form our
perception of the world. By comparison, the camera is a light sponge that
captures and holds different brightness values and colors. In short, the camera
is a machine. We ascribe value and connotation to those brightness values
later, when we view the image as a representation of something we previously
saw. Again, the eye is active, the camera is passive and requires our active
and creative intercession to blend perception and interpretation within our
image.
Next posting: The mechanics of image recording.
