Correct exposure to get the desired photographs
The right exposure is whatever makes your subject look its best in the type of photograph you create. That means exposure is definitely subjective. However, most people know when an exposure is right or wrong. Overexposed photographs are overly light, and detail is lost in the highlights. Underexposed photos are overly dark, and detail is lost in the shadows. The key thing about exposure is that important detail, dark or light, is captured properly so that the scene is light or dark appropriate to the subject.
Unfortunately, the world typically offers up a range of tones greater than what is possible to capture with a sensor. First, you might not be able to hold detail throughout the image with your exposure. Most digital photos look their worst with any overexposure or very dark underexposure. Good exposure results from the appropriate combination of shutter speed, aperture, and ISO speed. Exposure can be determined solely by the camera, interpreted by you (as the photographer) and the camera together, or solely by you.
One advantage of using the RAW format is that RAW captures more tonal steps between pure black and pure white as seen by the sensor. The result is an image that allows more correction to exposure in RAW conversion software. Still, RAW is no magic bullet that fixes bad exposure. You still need to be sure you have not made an image too light or too dark because once bright areas become pure white, or black becomes pure black, no amount of adjustment retrieves detail in those areas.
If you are shooting in tricky light or you are shooting a scene that seems to be difficult
to meter correctly, consider using the auto exposure bracketing feature if it is available
on your camera. Auto exposure bracketing enables you to shoot three or more sequential shots, each with a different exposure. The camera automatically shoots at user-selected + and – exposure changes around the metered setting.