This is an automatic bulb ramp made with the Timelapse+. 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).
It was edited using Lightroom and LRTimelapse for keyframed adjustments. No deflicker was applied (or needed).
The ability to use the PC sync feedback is a new feature that will be available in a firmware update later this week.