When getting a cheap digital camera, you must begin working on your skills. The light is measured, reflecting the area of interest. It is the method used by the internal photometers cameras. It is very convenient because it is integrated into the camera and allows us more flexibility when shooting, besides being able to measure light in objects that cannot be achieved. This type has the problem that if it reflects too much light the camera's metering may not be correct. They have therefore designed several types of measurement of light reflected different.
                             

To measure the reflected light DSLR cheap digital camera models have a measurement system called TTL (Through the Lens). As the name suggests this system uses light passing through the objective to make the measurement of reflected light. It consists of a sensor that is capable of measuring light from different parts of the scene. This frame is divided into zones (typically 16, 21, 35, 63 depending on model) and depending on the applied measuring mode or other percentages to each area.
The camera modes will determine the outcome. Once again there is a huge importance of reading the manual of your camera. Almost everything I say here is explained in more detail with him. Still want to talk about more normal modes of using DSLR camera for all explained in the previous issue of exposure is not pure theory.

All DSLR cameras on the market have at least the following modes:
- Automatic (shown green and the box is almost automatic P)
- Priority aperture (Av)
- Priority exposure time (Tv)
- Manual (M)
- Automatic specific programs (sports, night portrait, landscape, macro, etc)

The price does not really matter. You can reach a quality yet affordable camera. Maybe your cheap digital camera can even have more modes, but these are the basics you'll use most. I will speak specifically of the top 4 shooting and did not go into detail on specific programs automatic. 
As we said in the previous topic, the exhibition is the balance between aperture, exposure time and sensitivity of the sensor. Thus, depending on the type of photography you want to do and depending on what we want to control then use a program or another. When taking a picture you have to ask why you want control of that picture, and depending on the cheap digital camera response using one way or another.