long exposure modes in Olympus cameras

introduction

nearly all digital cameras have 2 long exposure modes:
- Olympus Live BULB mode - press shutter to start exposure and release to terminate it
- specific timed - most cameras have timed exposures of 1, 2, 4, 8, 15 and 30secs, Olympus cameras almost uniquely extend this to 60secs which is very handy indeed for astrophotography
  - most cameras also allow dark frame thermal noise frames to be taken and subtracted automatically
in addition, Olympus has introduced some unique modes:
- Olympus Time mode
  - unlike BULB mode which is terminated on taking finger off the shutter button, Time mode requires a 2nd press of the shutter button so you don't have to use a remote shutter release or have your finger pressed on the shutter button during exposure
- Olympus Live BULB mode
  - during BULB exposures, the image is able to be viewed on the LCD screen as it “develops” allowing you to terminate the exposure when you think the exposure is adequate
- Olympus Live Time mode
  - similar to Live BULB but exposure is terminated when shutter button is pressed again (rather than released as with BULB)
- Olympus Live Composite mode
  - allows in-camera “stacking” of multiple exposures
  - this is fantastic for creating star trail type images with multiple short exposures