Keyboard and mouse combinations to get the camera where you want it
The Camera command (keyboard shortcut F6) will let you Show/Hide the camera in your viewports.
Note: The target will not stay in the exact location. It will stay in the same plane perpendicular to the camera. However, its position on that plane will change depending on where the cursor is located during the zoom.
MMW
CTRL + RMB
Rhino V3
Rhino V4
Lens Zoom - Camera and target stationary, lens changed to zoom Alt + Shift + Ctrl + RMB