The zoom functions available are listed below:
This function is used to Zoom In and Out of the active window by using the mouse control.
Procedure:
•Click on View 
Set View Dynamic View 
Zoom In/Out (Ctrl+Z)
OR
•Click on the Zoom In/Out icon in the View Manipulation toolbar.
OR
• Click the right mouse button and select Zoom In/Out in the Graph window. Click and hold the left mouse button while moving the mouse up for zooming in and down for zooming out.
Note: This function does not manipulate the parts coordinate system. This is for viewing purposes only. To modify the part or assembly coordinate system use the Translate/Rotate function.
This function uses a drag rectangle to re-display the contents of the Graph or Tree window. It is used to view specific portions of the Graph or Tree window up-close, by changing its view scale.
Procedure:
•Select the Graph window or the Tree window, as desired, and click View Set View Dynamic Views 
Zoom Window (CTRL+SHIFT+Z)
OR
•Click on the Zoom Window icon in the Graph window.
OR
•Click the right mouse button in the Graph window and select Zoom Window in the menu,
•This puts the Graph/Tree window in the Zoom In mode. Hold the left mouse button down and drag the rectangle to enclose the portion of the Graph or Tree window that needs to be displayed.
•Release the mouse button when the required area to be displayed is completely enclosed in the dragged rectangle. The enclosed area is then re-displayed in the entire window.
•The Zoom In function does not automatically close after a Zoom has been performed. If the Zoom Window icon is depressed, the command is still active. Click on the Zoom Window pulldown or Icon again to deactivate the command.
By Percent
This function is used to Zoom In and Out of the active window by a set percentage chosen by the user.
Procedure:
•Click on the desired percentage you wish to Zoom In/Out by in the Set Zoom % drop-down in the Standard Views toolbar. The Zoom In and Zoom Out buttons will continuously repeat zooming in/out the set percentage, if the button is held down. If the Zoom In function repeats too quickly, the 1Step option in the drop-down will disable the continuous function, and Zoom In 90% per click.
•Click the Zoom In icon to make the image smaller and the Zoom Out icon to make the image larger.
Available buttons:
•Zoom In: expands the Graph window content by the Set Zoom %.
•Zoom Out: shrinks the Graph window content by the Set Zoom %.
•Set Zoom %: indicated the percentage used to zoom in and out the Graph window content.
•Set Zoom Scale: represents the zoom scale ratio. The 100 setting is an absolute scale value instead of the 95% relative setting (relative to the current scene for use with the +/- buttons). It also has no effect on the navigation window, so that if the navigation window is active and you change its value, it will return to the 100 when you reactivate the graph window. However, if you change it when the graph window is active, you will get a scaling effect.
Note: The 100 setting for the Set Zoom Scale has no effect on the Spaceball. The optimal settings for sensitivity of the space ball and culling threshold will be model dependent, as model size will make a big difference.