Some cameras allow you to choose among a list of possible photo situations where slight modification of exposure might be required. These could include a Night Mode and a Sports Mode, among others. Another important factor is how the camera determines the exposure. Some cameras may calculate the amount of light from the center of the image in the viewfinder. Other cameras may calculate the amount of light based on an average of the full image in the viewfinder.
Some cameras provide a choice.
A few higher-priced SLR cameras provide an optional selection of viewfinder screens for different exposure and focus selections. SLR camera models may offer even greater versatility with automatic, semi-automatic and manual exposure controls. Most cameras have fully automatic exposure. Some cameras also have a Macro Focus mode. It is designed to provide additional light, when needed.