In camera. It does pretty good. Good enough that I can forget about doing HDR in post now.
Works a little like "hand held twilight mode" in that it takes multiple shots and makes one shot out of them except "hand held twilight" is pretty much on auto and bumps the ISO way up with no control over aperture.
I checked the focus with focus peaking and I think the aperture was at 7.1. I have started using focus peaking nearly all the time to check focus. Real handy for checking DOF.
Brought back about 120 pounds or so of fish too. My wife was shivering in the car while I stood there shooting. Too dim to get shots of all the eagles flying around.
In these situations where the light is iffy, I generally will trust the cam with the HDR multi-shot jpeg or multi-shot noise reduction jpeg. I have tried the jpeg/RAW setting and while it allows you to bring some of the highlights up, it never can match the in camera HDR no matter how much time is spent later in post. Plus with a 18Mb size jpeg, you do have a little wiggle room in post if need be because there is a lot of info in that file.