Excellent Bulp Ramping Tutorial from Joel Schat on Bramping (bulb ramping). Bramping is a time lapse method of using an external hardware/software device to gradually alter the bulb setting on your camera for capturing the variable lighting condition for sunrises and sunsets. This is often referred to as the “holy grail” of time lapse.
Mentioned in the video are LRTimelapse from our friend, Gunther Wegner (www.lrtimelapse.com) and the Promote controller from www.promotesystems.com. Note that the Little Bramper mentioned in the video is no longer available.