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X
Firstly, delete default cube and camera
Center the cursor shift + 'S' cursor to center
Add first camera shift + 'A' Add camera
Set in front looking the camera. 'r' (rotate) '90' '-' to -90º
Locate it at know distance, i.e. -0.1 in the x axis
Duplicate the camera shift + 'D' and locate it at 0.1 in the X axis.
Add an empty. It will be the tripod. Shift + 'A' Add empty
Add a constraint for the second camera as it shown
Add an empty
Parent the cameras to the empty ctrl + 'p' make parent
The right camera is moved to 0. Although it has been moved due to the constraint
Now limit the camera movement to the X axis with another constraint
Next we can use the tripod to frame and the right camera to modify the interaxial distance
Add a new empty between both cameras, by placing the the cursor at (-0.05) in X ;-)
Move the empty in front of the cameras and name it as convergence point
Track cameras to the empty. ctrl + 'T' Track to constraint
Parent the empty "tripod" to the empty "convergence point"
Now we can frame with the empty "tripod", select the interaxial with the right camera and establish the convergence point with the empty "point of convergence"