How to use Focus in DSLR camera.

Once you know how a DSLR camera works the next step is to start using while understanding the Camera controls. In case you are using a DSLR camera in manual or semi manual mode then you can control all of these or some of the functions depending upon the settings

• Focus
• Shutter Speed
• Aperture
• ISO

In full automatic mode you don’t have an option to adjust these functions (except for focus).

Focus: It is more like an option available for the lens. If you will look carefully you could see a switch on the lens which says “Auto” and “Manual”.  The effect of both the options is quite similar and it depends upon the user how comfortable the user is while using it.

When “Manual” option is selected, it makes you control the focusing part of the lens. The rear end of the lens is kind of a moving ring. You can move it in clockwise or anti clock wise direction while pointing at a certain object thing then you could see that the image would get clear or unclear.  So, through this you can make adjustments and make the background of the image blur while making the subject more appealing. On the other hand certain subject can be made blur and background more clear.

In case, you choose the auto focus mode these are these followings options

AF-C (AF continuous, sometimes called continuous servo) is good use while capturing moving objects. When your camera is set to AF-C and you focus on a moving subject, for example a dog running towards you, the focus will stay on the animal as long as your shutter button is held half way down. In other words, the camera will keep on re-focusing the animal moves as long as you keep your shutter button held half way down.

AF-S (AF single, sometimes called single area AF) mode is used for capturing subjects that don't move, such as flowers, portraits etc. It locks the focus on the non moving object that you want to photograph. You can then recompose the shot and take the photograph.

AF-A is where the camera selects and goes between the last two modes. If it thinks the subject you are photographing is stationary, then it will automatically use AF-S focus mode. If it picks up that the subject you're photographing is a moving subject, then it will automatically use AF-C focus mode. This is also the default camera focus mode, unless you change the setting to AF-C or AF-S.

In Auto focus mode the camera also provides you with an option to control the focus points.  Focus points can range from 3 to 54 or more depending upon the camera. 

By controlling these points a user can choose on which part he or she needs to put more focus.

The points can be controlled under the AF-Area Mode and has these options

Dynamic Area AF:  Depending on which D-SLR you are using—you can select from several focusing options—9, 11, 21, 39 or all 51-points AF.

Single Area AF: Select a Single AF point and the areas surrounding it serve as backup—a significant advantage when shooting moving subjects. Select the 9-point option when you want to focus on erratically moving subjects with greater accuracy. When dealing with insufficient contrast for fast focus detection, choosing 21 or 51 points makes detection easier. The 51-point option also allows for 3D Focus Tracking, which uses color information from the 1,005-pixel RGB sensor to automatically follow moving subjects across the AF points.

Auto Area AF : It uses color information and special face recognition algorithms to automatically focus on an individual’s face, which is extremely helpful when there’s simply no time to select a focus point, or when using Live View in hand-held mode at high or low angles.

In the image the front part (tree branches) has been made clearer and the back ground has been blurred. The focus settings are AF- Single point with Dynamic Area AF.