EXFO OTDR 2 - Manual (Page 118)

Analyzing Traces and Events
110 OTDR
Using Zoom Controls

When you zoom in or out on the selected event, the application keeps
the zoom on this event until you select another event or change zoom.
You can select a different event for each wavelength (for example,
event 2 at 1310 nm and event 5 at 1550 nm). The selected events will
be saved along with the trace.
To view specific portions of the graph:

You can define which portion of the graph will be visible by selecting
the
button and dragging the graph with the stylus or your finger.
This could be useful, for example, if you want to zoom in on events
located outside the defined fiber span.

The button is the zoom selector. It allows you to select whether the
zooming will be performed according to the horizontal axis, the
vertical axis, or both.
Tap and hold this button to select the zooming direction in the menu.
Then, define the zoom area with the stylus or your finger (a rectangle
with dotted lines will appear to help you define the area). Once you
release the stylus, the application automatically zooms in on the graph
according to the zooming type you have selected. All of the other zoom
buttons (except for the zoom on selected event button) will reflect your
selection and behave accordingly.