The Zoom All option will automatically scale the model in the active view, so that all parts of the model are visible.
Zoom All is useful for quickly restoring the whole model to view, if you have been using the other Zoom options (e.g. Zoom In , Zoom Out , Zoom Window , Zoom Mouse ), or the Pan option.
Zoom All is available in:
The Zoom sub-menu of the View menu
The default right-click menu
The F2 function key.