Zoom Realtime
The 3D View | View | Realtime command zooms in and out as the left mouse button is held down and the mouse is dragged up and down in the plot window.
Enter Zoom Realtime Mode
To enter zoom realtime mode, click the 3D View | View | Realtime command, or the 
button in the plot window. The cursor will change to a 
to indicate that you are in zoom realtime mode. Hold down the left mouse button and then drag up or down in the window to zoom in or out. As you drag the mouse up, the screen is zoomed in. As you drag the mouse down, the screen is zoomed out.
Exit Zoom Mode
Click another tool or press the ESC key to end zoom mode.
Zoom Realtime With A Wheel Mouse
You can use a wheel mouse to zoom realtime and pan in the plot window or grid node editor. Rotate the wheel forward to zoom in, or rotate the wheel backward to zoom out. Hold down the wheel button straight down, and the cursor will turn to a closed hand. When the cursor is a 
, drag the mouse to pan the plot window. Be sure to click straight down with the scroll wheel. The zoom is changed so that the cursor location remains on the screen.
Zoom with the Keyboard
You can use keyboard commands to zoom in and out of the plot window. The default commands are CTRL + EQUAL SIGN (=) to zoom in, and CTRL + HYPHEN (-) to zoom out.
See Also
Zoom Realtime