Nature Photography Photo Workshop

2.1. HUMAN VISION AND PERCEPTION

The first thing to consider is how human vision and perception work. Most people have two eyes situated side by side; this simple physiological fact establishes the initial conditions for how your vision operates. Using two eyes allows you to perceive depth and dimension between objects near and far.

The placement of your eyes also results in a naturally horizontal orientation for your field of vision. In fact, the normal human field of vision is essentially a horizontal ellipse, with the outside edges and corners (peripheral vision) not being as clearly defined as the center, as shown in 2-1. This fact helps explain why the most comfortable orientation for a landscape photograph is horizontal — it's consistent with how you see the world.

Taking the signals from your eyes, your brain completes the picture in your mind, forming your total comprehension of what you're seeing. Most people generally see the world in the same way and vision is something you usually take for granted. However, there are many possible variations.

Figure 2-1. ABOUT THIS PHOTO Image of Tuscany, Italy, shows the approximate shape of normal human vision (ISO 100, f/18, 1/6 sec. with a Canon EF 28-135mm IS lens). To the human eye the central part of the scene is in sharp focus and the outer edges become indistinct; I simulated this effect in Photoshop by creating a rounded box and blurring the outer edges.

Conditions like color blindness and near- or far-sightedness affect ...