Depending on the capability or your camera, either through dials or through menus, you may find different exposure modes. They differ between camera manufacturers, but they share many similarities. Because they are all linked to the same internal light meter in the camera, all except for Manual will give, or attempt to give, the equal exposure to any other mode; the difference between them is how they balance the values for Aperture, Shutter Speed, and ISO.
•Full Auto = Fully automatic mode where the camera takes care of everything.
Fully automatic modes for a particular Subject:
•P = Program AE Mode
P: Program AE
If you have a limited understanding of when to use slow/fast shutter speeds and small/large apertures, start by using the P mode.
A creative tool that you can use in "P" mode is called Program Shift. Lets say that the recommended exposure for a scene is 125 8.0 (1/125 sec at f8). You decide to use a faster shutter speed to prevent the effects of camera shake. You turn the main dial and the camera now recommends 500 5.6 (1/500 sec at f5.6). Basically, the camera shifted the exposure values while still allowing the same amount of light to expose the sensor.
Tv: Shutter-Priority AE
A creative use of shutter speed is using slow shutter speeds to blur an image and give a sense of motion. Conversely, fast shutter speeds freeze motion.
Shutter Speed Display
Av: Aperture-Priority AE
The "standard" sequence of aperture values (f) is:
1 1.4 2.0 2.8 4 5.6 8 11 16 22
You may have noticed that your camera displays additional aperture values such as 7.1 and 9. The most important thing to remember about these numbers is that the smaller numbers (1.4, 2, 2.8, 4) represent large openings (apertures) in the lens and the larger numbers (11, 16, 22) represent smaller openings (apertures) in the lens.
When smaller f-numbers are used, less of the foreground and background are in acceptable focus. When larger f numbers are used more of the foreground and background are in acceptable focus.
The term depth of field is closely related to aperture values. Depth of field is defined as the area of acceptable focus that stretches from foreground to background. When photographing a person or a single flower you want that area to be narrow but when photographing a beach or a city/town that area should be as wide as possible.
M: Manual Exposure
In this mode you manually set the shutter speed and the aperture to suit the lighting condition. One of the best ways to determine the correct exposure is to use a commercially available handheld light meter.
Alternatively, you can use the exposure level indicator in the viewfinder to help you get the correct exposure.