To Dolly the Camera in 100 (Unit) Steps

Select the Define Camera tool.
In the tool settings window's icon bar, click the Dolly icon.
Turn off Continuous View Updates.
If necessary, click the More button to reveal the settings options.
Click the Show Controlled Movement button.
The Controlled Movement settings appear, with fields for Increments in Distance and Angle.
In the Distance field, type 100.
In the camera view enter a data point in the top, bottom, left or right of the view.
The camera is dollied 100 units in the direction determined by the location of the data point (in or out of the view, or sideways).
Further data points dolly the camera in 100 unit increments.