What is depth of field
What is depth of field | ||
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Your lens aperture is an important control for dimming or brightening images – helping to compensate for bright or dim subject conditions. But it has an even more important effect on visual results whenever you photograph scenes containing a number of items at various distances from the lens. Imagine for example that the shot consists of a head-and-shoulders portrait with a street background behind and some railings in front. If you focus the lens to give a sharp image of the face and take a photograph at widest aperture, both the street and railings will appear unsharp. But if you stop down to, say, f/16 (giving more exposure time to compensate for the dimmer image) you are likely to find that everything appears in focus from foreground through to background. This changing 'zone' of sharp focus, nearer and further than the object distance on which you actually focused, is known as depth of field. Depth of field is the distance between the nearest and furthest parts of a subject that can be imaged with acceptably sharp detail at one focus setting of the lens. Widest aperture (smallest f-number) gives least depth of field, while smallest aperture (highest f-number) gives most. There are two other significant effects:
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