This is an automatic bulb ramp made with the Timelapse+. This clip is not edited in any way -- it's just the raw files straight off the camera, converted to JPG in Lightroom (without adjustments) and then assembled with Quicktime 7 at 30 fps. The edited version van be seen here: vimeo.com/97141464
The starting exposure was 1/20s, f/5.0 (lens-twist), ISO 50, and it ended at 30s, 6400 ISO. The results are incredibly smooth using a PC sync cable to improve the timing. The PC Sync cable was connected to the AUX port of the Timelapse+, and the camera (5DmkIII) was controlled via USB by the Timelapse+ (no shutter cable).
The ability to use the PC sync feedback is a new feature that will be available in a firmware update later this week.