ExposuresWhen a modern camera first looks at what you are trying to take a photo of, it makes a guess at the proper exposure for that scene. However, if something in your scene is very bright - like a brightly lit wall behind the person you're taking a photo of - the camera could guess wrong. This would then cause the camera to assume the whole scene is bright, and the person will end up quite dark.
What you need to do in this case is manually override the exposure. Let the camera know that the scene you want to take a photo of isn't as bright as the camera thinks it is.
If the subject is close enough, you could also use some flash. The flash would light up the subject, to add more light and help offset the light which exists in the other part of the image.
So here is a person who is sitting by a very bright wall. The result is the camera thinks the wall is the brightness level to care about, and it adjusts for that bright wall. That ends up with the person being in shadows. By manually reducing the exposure, and also adding a flash, the result is more balanced.
You can't affect a landscape with a flash - the flash isn't that powerful :). So all you can do is change the exposure and do the best you can.
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