Use “Zoom Window” to define an area of the scene you want to zoom on.
To use this tool:
1. Select the “Zoom Window” tool (“1” key or 
icon of the Control Panel).
2. A white rectangle with an X at its center is displayed.
3. Place the cursor at the center of the area you wish to zoom into and click.
4. Drag the cursor to increase or decrease the size of he window.
5. Click when the whole area you want to zoom into is inside the boundaries of the white rectangle. The area contained in the white rectangle will replace the previous view on your screen.