Yesterday, I was in a the woods near Susquehanna, Pennsylvania, shooting this:

An abandoned schoolbus, once used as a hunting lodge for locals now long forgotten.

No light except available. You can see what lens I used, yes? Wide angle – 16mm (On a full frame camera).

As for settings, how did I arrive at the right settings?

1. I set the camera to Manual mode.
2. I wanted f/4, so I set that first.
3. Then I wanted a sufficiently fast shutter, say 1/40th sec or faster – at least 1/15th second when using a 16mm angle, to avoid camera shake. So I set that.
4. So that led to the ISO setting – I set the ISO so my meter indicated “-1 stop” when I aimed the camera, zoomed out, at an “average” scene (why -1? Because it is dark. Why not -2? BEcause I am ever so slightly “exposing to the right”, and I do not want to lose the highlights.

So that gives you:

And sometimes, a little adjustment in post: pulling back the highlights in the RAW image, and perhaps increasing the shadows’ brightness, to avoid the inside being all back or the outside all blown out:

Shooting contrasty scenes like this is not easy. So a trick you can use: go to Program Mode, with auto ISO, and see what settings this mode uses, then disable Auto ISO and go back to Manual, and emulate those previous settings; then fine-tune and adjust to taste.