PHOTOGRAPHY.
The process of photographing consists of three sequential steps: the choice of the subject, i.e., find the frame of the viewfinder, focus has been (focusing lens) and exposure (the choice of shutter speed and aperture).
Focus has.
When shooting multiple objects located in space at unequal distances, it is desirable, if conditions permit measure the distance from the camera to the foreground and background. If the subject is a separate subject, the focus has been to produce at a distance at which this subject. In that case, when the Live space has too much depth as you want to remove several items located at equal distances from the camera lens, you need to find an intermediate point with respect to it and focus lens.
To achieve the sharpness of the background if that is at the infinity focus adjustments must be done at a distance equal to twice the distance from the camera to the foreground, providing the necessary sharpness of the lens aperture.
Depending on the focal length of lenses have different features in the coverage of the shooting scenes of space, which in photographic practice is expressed in angular measure. Frame sizes in the device remain constant, so we can assume that the corners of the image are determined by the focal length of the object. The normal lens has an angle of the field represented close to 48 ° lens with small focal length gives a wider angle image, and a large - correspondingly smaller.
Using lenses with different focal lengths when shooting with one point you can get different angles and different image size, which would correspond to the total, medium and close-up.