The digital cameras offer a large number of options, as focalization is concerned, the automatic focus, the semi-automatic one and different settings will all help the photographer to reach a certain point.
When photographing a dynamic scene like people running, cars, bicycles, planes or animals moving, usually random scenery can turn in the most frustrating photo experience.
If the focus is not set properly a picture can turn into a mixture of foggy shades and colors, resulting in a mess.
When focalization fails the photography becomes a torment. If the camera is focused on a certain point the subject is going to reach, with a bit of synchronizing the photo will be better than if you use manual focus.
When taking pictures through glass the auto focus of camera will not function well because the auto focus will get “confused”. The manual focus will fix the problem so if you just ignore the glass and focus on the subject beyond it you can get the best shot and with a little skill ignore completely the glass.
As portraits are concerned the picture must emphasize a certain face feature, the eyes, the lips, the nose and the focalization must be very accurate.
With manual focus the photograph will control the picture completely and capture the exact feature the digital photographer intends to make memorable.