Wide ApertureSmall f #“Open”Shallow depth of

fieldFaster shutter

speed

Narrow or small ApertureLarge f #“Stopped down”“Closed down”Greater depth of

fieldSlower shutter

speed

Modern Camera Lenses are actually comprised of “groups” of individual lenses, or “elements.” These elements work together to form a compound lens, with its own traits and characteristics.

Characteristics & qualities of lenses

Focal LengthSpeedAngle of ViewMacroAuto-FocusImage Stabilized

Undesirable traits of a lens

DistortionAberrationChromatic AberrationVignette (drop off)Flare

Simple Converging (Convex) Lens

Lens Axis

F(Focal Point)

F(Focal Point)

FocalLength

All light that enters a lens parallel to the lens axis (collimated) is refracted at such an angle that it passes through the focal point.

Light that enters the lens after passing through the focal point, leaves the lens parallel to the lens axis.

Light that enters the lens parallel to the axis leaves the lens at angle that sends it through the focal point behind the lens.

Light that enters the lens and passes through the exact center of the lens is (relatively) undisturbed in it’s trajectory.

Object at or inside focal point of lens, no image can be formed.

Simple Diverging (Concave) Lens

Forms a Virtual Image, as opposed to a Real Image.

When an image is formed, it is a round image, the periphery of which is called theImage Circle.

The film , or sensor, must fit entirely inside this circle, or vignetting and imagefall-off will occur.

Scene

Scene

Film

Film

Film

Print

Scene

Film

Print

Color Negative film works in a similar fashion, but with 3 separate sensitive layers:

Red sensitive layer forms Cyan dye according to quantity of Red light.

Green sensitive layer forms Magenta dye according to quantity of Green light.

Blue sensitive layer forms Yellow dye according to quantity of Yellow light.

Color Transparency film forms a negative image as with B&W, but it also has a secondary development step in processing during which a POSITIVE dye image is formed in

response to the negative image created through exposure and first development.

Photography dwells in the world of ADDITIVE COLOR, wherein the primary colors are Red, Green, and Blue. This as

opposed to SUBTRACTIVE COLOR, wherein the primary colors are Red, Yellow, and Blue.