bulb ramping not smooth

[spejampar]

First, I apologize if this has been asked before. If so, please guide me to the thread.

When I do a sunset or sunrise bulb ramp on the 60D, it mostly works fine, but at certain times, all of a sudden, the exposure jumps.  I think it has to do with hitting the ISO limit so it jumps to a new shutter speed which results in a much brighter or darker image than the previous one which is adjusting the exposure in the opposite direction than I want it to.  For instance, when I bring sunset images into LRTimelapse, the exposure line typically goes down a bit.  But at these "jump" frames, that exposure line jumps up, then gradually falls like it's supposed to, then jumps up again later, and repeats periodically. 

Anyone know why this happens and more importantly what I can do to fix it, if anything?  I really don't want to have to manually adjust the exposure in bridge/lightroom after the fact.  I haven't found an easy way to fix this in LRTimelapse either.
Thanks!

[dmilligan]

bulb ramping was scrapped a long time ago in favor another method:
http://www.magiclantern.fm/forum/index.php?topic=5705.0

With that method you get lots of exposure jumps, but you simply fix them in post with some sort of deflickering tool. Here is one such tool that I wrote: http://www.magiclantern.fm/forum/index.php?topic=8850.0