Bulb Ramping allows the capture of a timelapse that gradually changes exposure, compensating for the transition from day to night.
This option will adjust shutter and ISO automatically, using the 180 degree rule.
Quick start:
1. Take a picture of your scene. You will use it to say: "I want my timelapse to be exposed like this picture".
2. Enable Bulb Ramping and Intervalometer.
3. Leave the camera still while ML runs a calibration step:
Make sure you have a static and well-lit scene (any static scene which does not require long exposure should be fine).
After calibration, you should get a nice S-curve on the screen.
4. Now you will have to say what tone range to meter for (i.e. highlights, midtones...). Follow the wizard:
Use arrow keys to select your reference picture (which you just took).
Use the main dial to select the tone range to meter for. You can't perfectly match two images just by varying one parameter (exposure), so you have to choose what's important for you in this picture.
For lowest flicker, meter for midtones (choose the 50th percentile, i.e. median). Leave some headroom for highlights (underexpose a bit).
If highlights are important, meter for them (choose 80th percentile for example). You will get more flicker; shoot RAW to remove it easier in post.
The algorithm works best when brightness is close to 50% (try not to choose extreme values for it).
When you are ready to start, press SET.
5. Sit back and relax