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

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).