The Mars Descent Imager for NASA's Mars Science Laboratory took this image inside the Malin Space Science Systems clean room in San Diego, Calif., during calibration testing of the camera in June 2008. It shows the instrument's deputy principal investigator, Ken Edgett, holding a six-foot metal ruler that was used as a depth-of-field test target. The camera is focused at 7 meters (23 feet) so that everything between about 2 meters (7 feet) and infinity is in focus. This image shows a slightly out-of-focus rock (a rounded cobble of Icelandic basalt with tiny crystals and vesicles) at a distance of about 70 centimeters (2.3 feet), equivalent to the distance the camera will be from the ground after the rover has landed.