If you look at the ARTICLES above, you will see one about “exposing to the right”. Read it. And perhaps remember this as a “take-home” outcome:
Provided you do not actually overexpose any of the channels (Red, Green Blue), you can always reduce brightness in all or part of the image in “post”, and as a result of doing this increase the quality compared to shooting it darker in the first place.
That is why we expose to the right. I am not advocating doing this all the time, mind you: it would mean post-production work all the time, and we are photographers, not graphic artists. But sometimes you simply do not have the time to put up lights.
When I shot that, I knew I would want the ambient light darker. But that would have meant getting out the softbox, boom, pocketwizards, and so on; and that simply was not practical at the time. So I shot like in the pic above, knowing that I could reduce—not increase— exposure in part of the image later by way of masking or vignetting.
With a little work, and I mean a little (perhaps a minute or two), that gives me something like this as an end result:
Now again, of course it is much better to actually shoot this way. But when you do not have a choicer, expose as highly as you can without overexposing either of the three primary channels; then, reduce locally later to taste.