OS X El Capitan: Zoom options in Accessibility preferences
Set options for the selected zoom style (full-screen or picture-in-picture) by clicking More Options in the Zoom pane of Accessibility preferences.
To open this pane, choose Apple menu > System Preferences, click Accessibility, click Zoom, then click More Options.
Fullscreen zoom
| Maximum Zoom and Minimum Zoom | Set the magnification range to use when zooming in and out rapidly. |
| Show preview rectangle when zoomed out | Display a rectangle on the screen that shows the center point of the zoom. Drag the rectangle to the area where you want to zoom. |
| Continuously with pointer | Make the zoomed image move with the pointer. |
| Only when the pointer reaches an edge | Prevent the zoomed image from moving until you move the pointer to an edge of the screen. |
| So the pointer is at or near the center of the screen | Keep the center point of the screen near the pointer as you move it. |
Picture-in-picture zoom
| Magnification (x) | Set the magnification in the zoom window. |
| Window position | Set whether the zoom window stays in one location on the screen, follows the mouse cursor around the screen, or is tiled along an edge of the screen. |
| Cursor style | Set the cursor style used in the zoom window. |
| Invert colors | Set the display of the zoom window to the opposite of the screen display. For example, if the screen display is showing black on white, the zoom window displays white on black. |
| Enable temporary zoom | Display the zoom window when you hold down the Control and Option keys together. |
| Speak items under mouse after delay | Set how many seconds the system waits before it speaks the items that are under the pointer. |
| Adjust size and location | Open the zoom window to resize and reposition it. Resize: Drag any edge or corner of the window. Reposition: Drag the window to a new location, or to an edge of the screen. |