9.5.2

310 • CHAPTER 7
OBJECTS MENU • CAMERAS • 311
The camera model used in computer graphic programs corresponds to a
pinhole camera of innite sharpness. Therefore CG focal length is to be
understood only as a simulation and corresponds in no way to a physical
model.
Short focal lengths give a wide-angle view and are ideal for a good overview of the whole scene. They
do, however, distort objects in the scene — a particularly striking effect is that of a very short focal
length. Large focal lengths correspond to a telephoto lens and display a very small area of the scene
since only a small spatial angle can be captured.



Lens type Focal Length
Fish-eye 20 mm
Wide-angle 35 mm
Normal 50 mm
Portrait 85 mm
Telephoto 200 mm
Super telephoto 1000 mm
The advantage of a telephoto lens is that you can capture detail with hardly any distortion. With an
extremely high value used as a focal length, the perspective depth is lost completely as the perspective
projection changes into a parallel projection.
Aperture Width
The Aperture Width parameter corresponds to the size of the opening in a camera (the aperture)
that allows light to pass through the lens onto the lm. The ratio of the Aperture Width to the Focal
Length determines how much of the scene (the ‘viewing volume’) can be viewed through the camera.
For example, if you double both the Focal Length and the Aperture Width, the viewing volume is
unchanged.
Field of View
A measurement for the camera’s angle of view. The greater the Focal Length, the smaller the Field of
View.
Zoom
This setting is not available if Projection is set to Perspective.
The Zoom setting allows you to zoom the view. It denes the scaling factor for the view.