This post was last modified: 2016-03-10, 00:20 by
Gunther.
Av mode is not controllable. It will make the images too bright when it gets dark (metering stops working from a certain darkness on) and further on you would have to combine it with Auto ISO and you can't really control how the camera will set Exposure/ISO and what it will prioritize.
So normally I recommend using qDslrDashboard and the Auto Holy Grail, it allows for a full 3 way ramping of Shutter, ISO and Aperture. And you get a nice preview on the tablet including Histogram and can jump in any time during ramping if you feel the images should get darker or brighter. The steps will be 1/3 and LRTimelapse's Holy Grail Wizard will smoothen those and the visual deflicker at the end will do the remaining smoothing.
Wir RP it's quite similar - just set it to ramp exposure and ISO (don't know about aperture) - but don't use Bulb ramping. Then you can use the same workflow in LRTimelapse. No need to use the RP XMPs, since LRTimelapse's Auto Holy Grail will do the same job.