Just getting started with photography, most beginners make the same mistake. There are always photos that fall prey to these mistakes before they can understand and use camera technology. Even after getting through the getting started stage, photographers can make mistakes from time to time in later shots.
First of all, let me explain: The "mistake" we have made in this section is based on the recognition that the purpose of photography is to take a picture that is correctly and clearly exposed. However, that does not mean that you can not make distinctive photographs that may violate our generally accepted photographic purposes in an artistic and groundbreaking way. Often, before we innovate, we should be well-versed in certain photographic techniques.

Overexposed

If you have a white, unskinned area in your photo, the picture is overexposed. In other words, the amount of light received by the sensor is much greater than the amount of light required for proper exposure. The reason why this happens, usually because of the ISO value, aperture and shutter speed of the combination of problems, of course, with the brightness of the filming site. In principle, in order for the sensor to receive less light, the aperture can be shortened, the shutter speed can be shortened and the ISO value can be reduced, but before making such adjustments
Consider other factors.
The overexposed areas of the image can also be slightly dimmed by targeted post-processing so that you can see some details. Here to distinguish between overexposed area and lighter image area, because the latter may only look pure white, in fact, there are details. This difference can be seen when shooting through the histogram on the camera's display. If the image area is swallowed by white, then the right side of the histogram will be truncated.

If the image is overexposed, the bright image area will be swallowed by white. In other words, that area can not see any detail, only the pure white. Normally, this happens when you have a wrong metering or manually set the wrong one.

 

Insufficient exposure

Too little light to reach the sensor can cause underexposure, and this is the case because of a combination of aperture, shutter speed and ISO values. The end result is a pure black, no-detail area of the image. Worse, because of the amount of light is too small, the under-exposure area will form interference noise.
However, underexposure should not be overexposed if it is not possible to determine what to do better, as the white "erosion" has more information than the black "flooding" message. It is also important that you do not confuse overexposed and underexposed shots with low-cut and high-cut shots, although the main areas of light and dark tones appear in high and low-cut images, but there are details in these areas.

When underexposure, the sensor obtains too little light, so that the charge generated by the light and the sensor's own basic charge can not be distinguished. The result is usually: the area should be pure black appear unpleasant variegated and clear noise.