To Change the Lens View Angle in 10° Steps

Select the Define Camera tool.
In the tool settings window's icon bar, click the Lens View Angle icon.
Turn off Continuous View Updates.
If necessary, click the More button to reveal the settings options.
Expand the Controlled Movement section to display fields for Increments in Distance and Angle.
In the Angle field, type 10.
In the camera view enter a data point in the top or bottom of the view.
The lens view angle is increased by 10° if the data point is in the top half of the view and vice-versa.
Further data points change the focal length in 10° increments.