Auto ETTR Sunrise Timelapse

[dmilligan]

60Da, Canon 10-22mm
Cleanup in Bridge/ACR, Edited in AfterEffects
Interval Period: 45s (15s longer than slowest shutter to give Post Deflicker plenty of time to work)
AutoETTR + Post Deflicker
Av: f/4
Slowest shutter: 30"
Max ISO: 1600

[a1ex]

Hm, still flickers. Can you post an image thresholded at the percentile you used for deflicker?

(in gimp, move the histogram slider until you get that number)

Nevermind, did it myself from a screenshot. Here's how it would look with median (50th percentile) at the end of the image:



Post deflicker will meter on the edge of this image, so the edge should fall on something that should not flicker (here, it should cross the sky). In your example, the median falls on the right corner of the sky, which is not quite what you want.

If you meter at the 70th percentile, it will look like this (one of the last frames and one of the first ones):



I don't know what setting you used, but for this example I recommend trying to set the percentile to 70. Of course, if you change the framing, the percentile may change. To see where it falls, you can use a dirty trick: set 100-percentile as "highlight ignore" in ETTR and use the debug option "show metered areas".

I'm still thinking how to implement a way to choose the percentile automatically (in post it should be possible to analyze the footage and compute an optimal one somehow).

[dmilligan]

I probably just used the default of 50.

The problem is I have no way to know what the sky will look like 3 hours in the future when it is right now the dark of night, so choosing the correct median is just a shot in the dark (pardon the pun). Also, I had to set this up at like 4am whilst I was groggy and mostly asleep so trying to think about setting an optimum median percentile was way beyond my mental faculties at the time. All the more reason post deflicker needs to be a post tool.

[a1ex]

Yep, and I'll include this kind of debug images so you know what's going on.