I split exposure into two kinds, the first I call representational, where the aim is to accurately record and display tones and colours. This is typically used when photographing artwork and products. The other type of exposure I would call interpretational where the cinematographer/photographer uses the exposure to create an image rather than just record one.
The first thing to make clear is that when using exposure to create an image that interprets a scene there are no rules – it is down to personal taste. That said, for myself I see far too many images that are either flat or worse that have muddy blacks. This is either created during the exposure of the image or as equally likely during processing the image on the computer.
As an example here is a really well composed scene but the blacks have been lifted giving them a muddy look.
In the second image I have simply reset the blacks so that they are black. However this has resulted in a loss of detail in the left-hand corner of the room. Personally I think it draws the eye towards the subject.
If seeing the outline of the doorway is important in an ideal world you would shine a bit more light into the corner. Note the exposure is being set to keep detail in the white bandages – opening the lens would destroy this. If this is not possible then when processing the image as well as pegging the black level I would lift the mid-tones (third image).
In part two I will explore how to use the dark creatively.