If you select [On], you can extend the shutter speed when shooting in mode M up to 900 seconds (15 minutes). This is useful when you want to shoot with the shutter open for extended periods, such as for astronomical photography.
- At shutter speeds of 60 seconds and slower, the exposure time will match the selected shutter speed (when [On] is selected). When shooting starts, the control panel switches to indicate that the shutter is open.