Contax RTS II Gebrauchsanweisung Seite 37

For example, as shown in photo (1), you have a situation where
the background is excessively bright and you wish to place the
subject in one side of the picture ln this situation you can either
center the finder on the subject and set the AE Lock, or
approach the subject to take a direct exposure reading at close
range and then set the AE Lock Reposition the camera, reframe
your subject and obtain a picture showing good detail as shown
in photo (2)
To avoid unnecessary battery drain, arways return the AE
Lock lever to its original position whenever you are through
photographing.