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Exploring Photography
A lens is a transparent material that has
at least one curved surface. See Figure 3-1.
When light enters the camera, it passes
through a lens. The lens collects and bends
light rays. The rays are bent so they form a
sharp image on the fi lm or digital sensor.
See Figure 3-2. A lens can be made of special
optical glass or plastic.
Figure 3-2. The lens collects and bends light rays so they form a sharp image on the fi lm or digital sensor.
The reflected light is
gathered by the lens which
focuses it on the film or digital
sensor to make the exposure
Light is reflected
from the subject
Light from the sun
or an artificial source
lights the subject
Figure 3-1. A lens is a transparent glass or plastic
disc with at least one curved surface. Light passes
through it.
Simple Rules of Light and
Optics
To understand how a lens works, some
basic rules of optics, the physics of light, must
be known. Light usually travels in straight
lines, called rays. See Figure 3-3. If there is
nothing in the path of a light ray, it will con-
tinue in the same direction. Light rays can
be transmitted, absorbed, and refl ected. The
shape and properties of a material will deter-
mine what happens to the light ray after it
contacts the material. See Figure 3-4.
In the study of camera lenses, we are
mostly concerned with transmitted light.
This is the light that passes through the lens.
Transmitted Light
Light rays can travel through a trans-
parent or clear material such as water, glass,
and plastic. The light rays, however, are bent
as they pass through. The bending of light