Mechanical stimuli control multiple cellular processes such as secretion, growth, and differentiation. A widely used method to investigate cell strain ex vivo is stretching an elastic membrane to which cells adhere. However, simultaneous imaging of dynamic signals from single living cells grown on elastic substrates during uni-axial changes of cell length is usually hampered by the movement of the sample along the strain axis out of the narrow optical field of view. We used a thin, prestrained, elastic chamber as growth substrate for the cells and deformed the chamber with a computer-controlled stretch device. An algorithm that compensates the lateral displacement during stretch kept any selected point of the whole chamber at a constant position on the microscope during strain or relaxation (compression). Adherent cells or other materials that adhere to the bottom of the chamber at any given position could be imaged during controlled positive (stretch) or negative (compression) changes of cell length. The system was tested on living alveolar type II cells, in which mechanical effects on secretion have been intensively investigated in the past.