LEC 6 key concepts

MEDP/FILMP 150
SPRING 2009
ANDERSON/LUCAS

KEY CONCEPTS FOR CLASS 6

Adjustable Components of a professional-level zoom lens: focus, focal length, aperture (F-stop)

FOCUS

• determines what is sharp in the frame

• related to distance along the camera-subject axis – need to refocus when the distance between the camera and the subject changes

• selective focus

• rack focus

FOCAL LENGTH

• determines Angle of View

• measured in mm

• determined by distance from optical center of lens and recording surface

• prime vs. compound lenses

• relationship between numbers and angle of view depends on recording surface (different from 35mm camera and small video camera, for example)

• fisheye lens

• relationship between focal length Depth of Field

• shallow vs. deep depth of field

• long lenses compress space (and vice versa)

APERTURE

• controls amount of lens coming through the lens

• measured in F-stops

• each F-stop doubles (of halves) light entering lens

• F-stop impacts exposure (underexposed, overexposed images)

• F-stop affect Depth of Field (small aperture means deeper depth of field and vice versa)