Adobe After Effects CS4 - Manual (Page 194)

188 USING AFTER EFFECTS CS4
Layers and properties
Last updated 12/21/2009
Note: The three things that affect depth of field are focal length, aperture, and focus distance. Shallow (small) depth of
field is a result of long focal length, short focus distance, and a larger aperture (smaller F-stop). A shallower depth of field
means a larger depth-of-field blur result. The opposite of a shallow depth of field is deep focus—meaning a smaller depth-
of-field blur because more is in focus.
Name The name of the camera. By default, Camera 1 is the name of first camera that you create in a composition, and
all subsequent cameras are numbered in ascending order. You should choose distinctive names for multiple cameras
to make it easier to distinguish them.
Preset The type of camera settings you want to use. The presets are named according to focal lengths. Each preset is
meant to represent the behavior of a 35mm camera with a lens of a certain focal length. Therefore, the preset also sets
the Angle Of View, Zoom, Focus Distance, Focal Length, and Aperture values. The default preset is 50mm. You can
also create a custom camera by specifying new values for any of the settings.
Zoom The distance from the lens to the image plane. In other words, a layer that is the Zoom distance away appears
at its full size, a layer that is twice the Zoom distance away appears half as tall and wide, and so on.
Angle Of View The width of the scene captured in the image. The Focal Length, Film Size, and Zoom values determine
the angle of view. A wider angle of view creates the same result as a wide-angle lens.
Enable Depth Of Field Applies custom variables to the Focus Distance, Aperture, F-Stop, and Blur Level settings.
Using these variables, you can manipulate the depth of field to create more realistic camera-focusing effects. (The
depth of field is the distance range within which the image is in focus. Images outside the distance range are blurred.)
Focus Distance The distance from the camera to the plane that is in perfect focus.
Add this expression to the Focus Distance property to lock the focal plane to the camera's point of interest so that the
point of interest is in focus:
length(position, pointOfInterest)
Lock To Zoom Makes the Focus Distance value match the Zoom value.
Note: If you change the settings of the Zoom or Focus Distance options in the Timeline panel, the Focus Distance value
becomes unlocked from the Zoom value. If you need to change the values and want the values to remain locked, then use
the Camera Settings dialog box instead of the Timeline panel. Alternatively, you can add an expression to the Focus
Distance property in the Timeline panel: Select the Focus Distance property, and choose Animation
> Add Expression;
then drag the expression pick whip to the Zoom property. (See “ Expression basics ” on page 646.)
Aperture The size of the lens opening. The Aperture setting also affects the depth of field—increasing the aperture
increases the depth of field blur. When you modify Aperture, the values for F-Stop change to match it.
Note: In a real camera, increasing the aperture also allows in more light, which affects exposure. Like most 3D
compositing and animation applications, After Effects ignores this result of the change in aperture values.
F-Stop Represents the ratio of the focal length to aperture. Most cameras specify aperture size using the f-stop
measurement; thus, many photographers prefer to set the aperture size in f-stop units. When you modify F-Stop,
Aperture changes to match it.
Blur Level The amount of depth-of-field blur in an image. A setting of 100% creates a natural blur as dictated by the
camera settings. Lower values reduce the blur.
Film Size The size of the exposed area of film, which is directly related to the composition size. When you modify Film
Size, the Zoom value changes to match the perspective of a real camera.
Focal Length The distance from the film plane to the camera lens. In After Effects, the position of the camera
represents the center of the lens. When you modify Focal Length, the Zoom value changes to match the perspective of
a real camera. In addition, the Preset, Angle Of View, and Aperture values change accordingly.
Units The units of measurement in which the camera setting values are expressed.