T3i + Sunset bulb ramping time lapse weirdness? or just me?

[khiloa]

Hi all. I just installed ML 2.3 on my T3i and was going to give it a good test by recording a sunset time lapse of a scene of a field and trees. I set the intervalometer to an exposure every 4 seconds and set the bulb ramping to sunset mode. I can't remember for sure what I chose for the maximum ramping speed, but my best guess is 0.01EV. I calibrated it to the 50th percentile, as I wasn't sure which percentile would be the best for the situation. Please advise on appropriate settings.

Here's what I don't understand: The ISO was "stuck" at 100 the whole time, except for 1 individual frame near the middle of the sequence, which was captured at ISO 400. And after it got rather dark, the images were virtually completely black, given the ISO 100 limitation and 4 second exposure interval. Why did the ISO not increase? And is there not a way to lock in a certain aperture without locking it in by unscrewing the lens partially?

I spent a few hours last night reading over the user's manual, old forum threads, etc. but couldn't quite wrap my head around this behavior. Thanks.

[a1ex]

Did you allow it to ramp fast enough?

You can post the log file to see what went on.

[khiloa]

Here's the log file: http://pastebin.com/YdFBJ4Wi

Besides the really obvious info such as shutter speed, I can't really interpret what it says.

[khiloa]

Forgive my ignorance, but can someone at least explain why the ISO didn't increase from 100? Except for 1 random shot?

[a1ex]

Do you remember what did ML display as ISO range? (it usually shows 100-1600 or whatever you have in auto ISO menu).