Back ligtht

You know this situation: you want to take a picture of a person standing in the snow or at the beach and the sun shines from the back of that person. Setting your camera to automatic mode now will result almost certainly in a sub optimal photo ...

The face and the front of that person will be probably too dark on the picture, because the camera's automatic mode tries to set the exposure so that most of the photo will be exposed correctly. This will be true for the surrounding of the person, but not for the relatively small part where the subject is.

To avoid this, you can:

1. Set the exposure measurement mode of your camera to "spot" or "partial". This way only a small part in the center of the picture will be used to calculate the correct exposure. You should point the center of the image area to the subject and then press (and keep pressed) the trigger half way to store the exposure values. You can then choose the image section as you please and press the trigger all the way.
2. Set an exposure correction (try -2 steps).
3. Use flash. You might have to change from full auto mode to a different mode to use flash. You should also make sure you are not too far away from the subject otherwise the light from the flash will not reach it.

With point 1. and 2. the background might get over-exposed, but that's something you have to live with, because the camera only has a limited dynamic range. Point 3. decreases the dynamic range of the picture by lightening the subject, so the whole range can be captured.