This is something that can be tricky to understand so I will keep this as simple as possible. You camera whatever that is is programmed from the manufacture to capture certain amount of light in each shot. So when you are shooting something against white or bright light the camera will think there is too much light so it will Under Expose the image and when you are shooting something against black or dark area or at night then your camera will Over Expose the image to capture required amount of light.
So in which situation you would under expose, well this would be when your camera is compensating for the lack of light and Over Exposing the image. This is when you would want to Under Expose your image. To do this find the Exposure Compensation dial or setting on your camera and set the compensation for -1 or -1/3 stop. A ‘stop’ is just a unit of measure in Camera terms which defines how much light is captured, for example, 2-stops of light is double the light 1-stop would gather. The value you use, will depend on your creativity and how you want to capture the scene.
Here are some of my tips:
- At night – Exposure Compensation of -1 to -2 stop typically
- Against dark background – Exposure Compensation of -1/3 to -1 stop typically
Exposure Compensation can be used in any of these Shooting Modes in your camera, Program Mode (P), Aperture Priority (Av/A) and Shutter Priority (Tv/S). It doesn’t work when you are in Manual Mode (M).
Real World Example
In the image below, you can see that the pond is quite dark so what did my camera do? It tried to Overexpose the image but caused the lotus flower to become to bright. The petals are becoming too might so we can’t see the detail much in the flower.
Now to fix this, I adjusted Exposure Compensation dial to -1 stop and took another shot which is correctly exposed. We can see the individual petals and their definition.
These are un-edited images straight out of the camera. You can always enhance it further it Lightroom.