Autodesk AUTOCAD 2006, Command Reference Manual, Page: 435 / 1490

Toggle (Angle From)
Switches between two angle input modes. Entering an angle on the
command line locks the cursor movement so you see only the positions
available for that angle. Toggle unlocks the cursor movement for the angle,
and you can use the cursor to rotate the target.
Distance
Moves the camera in or out along the line of sight relative to the target. This
option turns on perspective viewing, which causes objects farther from the
camera to appear smaller than those closer to the camera. A special perspective
icon replaces the coordinate system icon. You are prompted for the new
camera-to-target distance.
Specify new camera-target distance <current>: Enter a distance or press ENTER
A slider bar along the top of the drawing area is labeled from 0x to 16x, with
1x representing the current distance. Moving the slider bar to the right
increases the distance between camera and target. Moving it to the left
decreases that distance. To turn off perspective viewing, click the Off option
from the main DVIEW prompt.
If the target and camera points are close together, or if you specify a
long-focal-length lens, you might see very little of your drawing when you
specify a new distance. If you see little or none of your drawing, try the
maximum scale value (16x) or enter a large distance. To magnify the drawing
without turning perspective viewing on, use the Zoom option of DVIEW.
Aerial View Window | 411