Camera and dof
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A camera is a device that records images as still photographs or moving videos. It consists of an enclosed hollow with an aperture for light to enter and a surface for capturing the light. Most cameras have a lens positioned in front of the aperture to focus the image. The depth of field (DOF) refers to the portion of a scene that appears sharp in the image. The DOF is determined by the subject distance. There are three variables that affect DOF - aperture size, subject distance, and lens type. A lower f-number aperture, closer subject distance, or telephoto lens will produce a shallower DOF while a higher f-number, farther subject, or wide-angle lens will increase the D
Camera and dof
- 1. CAMERA AND DOF (DEPTH OF FIELD)
- 2. WHAT IS CAMERA • A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura (Latin for "dark chamber"), an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura.
- 3. • Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. A majority of cameras have a lens positioned in front of the camera's opening to gather the incoming light and focus all or part of the image on the recording surface. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture.
- 4. • A typical still camera takes one photo each time the user presses the shutter button. A typical movie camera continuously takes 24 film frames per second as long as the user holds down the shutter button.
- 5. WHAT IS DOF? • In optics, particularly as relates to film and photography, the depth of field (DOF) is the portion of a scene that appears sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on either side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions. • The DOF is determined by the subject distance (that is, the distance to the plane that is perfectly in focus).
- 6. Control the Depth of Field • There are three variables that affect DOF, the size of the Aperture, the distance to the object and what lens are using. (There is a fourth thing that affects the DOF, but that’s the size of the sensor and unless you have two cameras with different sensor sizes this isn’t something to take into account.)
- 7. Changing Aperture • As you can see in the illustration above, a lower f-number equals a shorter depth of field. A higher f-number will give you focus over a longer distance — when you’re having a hard time getting the correct focus it might be a good idea to extend your DOF by changing the aperture
- 8. Changing Focus • The distance between you and the object is also important, the closer you are to the object the shorter the DOF. If you’re photographing a person but needs to have a high f-number you can still get a very short DOF by keeping the distance between you and the person to a minimum.
- 9. Changing Lens • The last thing you can do to affect your DOF is to change the lens. A wide-angle lens has a much greater DOF than a telephoto lens; the most extreme wide-angle and fish-eye lenses don’t even have to focus because they are so sharp on every aperture for the entire DOF (making for excellent scenic shots).