The depth of field is a basic photography concept that must be understood by every photographer for manipulation of image focus to create dramatic photographs. The depth of field can be defined as the range of sharpness or focus of an image, the larger the area of focus, the larger the depth of field while the depth of field is said to be shallow when the area of focus is small. To further explain with practical examples, an image whose object is a flower vase in front of a wall is said to be have a shallow depth of field, if only the flower vase is looking sharp but a scenario whereby both the flower vase and the wall behind are both in focus, it is said that there is a larger depth of field.
There are certain factors that affect how large or shallow the depth of field of an image will be and we will be discussing them in very simple language, avoiding the more complex physics explanation involved. Three factors we will be looking at are Aperture, the focal length of the camera lens and distance between camera and object.
The aperture is often the most deciding factor when it comes to the shallowness or largeness of the depth of field. The aperture is a small opening in the camera lens that allows light get to the image sensor, it is always shut but opens when the camera is fired. The wider the aperture opens, the more the amount of light that comes in, the brighter the image produced and the shallower the depth of field. When the aperture is smaller, the images produced are with a large depth of field.
The focal length is another important factor in deciding the depth of field of an image. If the focal length is longer; telephoto lenses, the image produced will most likely have a shallow depth of field while for shorter focal length; wide angle lens, you get images with very deep depth of field. A camera with a lens of about 400mm will produce images with very shallow field depth while that of 24mm will produce images with deep shallow depth of field.
The distance between the camera and object or focus distance is another factor that determines the depth of field of images. If you take a picture very close to an object, you will notice that in the image produced, the object in front is sharper and everything in background is blurry, which is why for group picture or landscape photos, images are captured from afar