20Concepts in PhotographyCorrelation between focal length, angle,and perspectiveFocal length, which is measured in millimeters, is the distance betweenthe middle of the lens to its focal point. It affects the angle and perspectiveof captured images. A short focal length translates into a wide angle,which allows you to capture a wide shot. A long focal length translatesinto a narrow angle, which allows you to capture telephoto shots.9 mm angle 27 mm angleDepth of fieldPortraits or still-life photos mostly acclaimed by people are the ones onwhich the background is out of focus so the subject looks pronounced.Depending on the focused areas, a photo can be blurred or sharpened.This is called 'a low DOF' or 'a high DOF'.The depth of field is the focused area around the subject. Therefore, asmall DOF signifies that the focused area is narrow and a large DOF meansthe focused area is wide.A photo with a small DOF, which stresses the subject and makes the restof it blurred, can be obtained by capturing a photo close to the subject orselecting a low aperture value. Conversely, a photo with a large DOF whichshows all the elements on the photo sharply focused can be achieved bycapturing a photo far from the subject or selecting a high aperture value.Small Depth of Field Large Depth of Field
