SUMMARATION
In this course I learned these
topics:
·
Photography
and the application :
- Camera types and characteristics
-
SLR
camera specialization and handling
-
Lenses
and aperture
-
Shutter
speed and exposure
-
Film
/ CCD and functions
-
The
sources and effect
-
Controlling
and manipulation
-
Natural
and available light
-
Artificial
and flash lighting
·
Close-up
photography:
-
The
strengths and importances
-
The
equipments and requirements
-
The
shooting techniques
·
Studio
photography:
-
Equipments
and techniques
-
Shooting still – life
-
Portrait
and living
-
Product
photography
·
Digital
photography:
-
Digital
camera and its controls
-
The
strength and techniques
-
Visual
modification using camera
-
Media
for visual storage
Ø And I mentioned some of
these topics as below:
Function
The camera or camera obscura is the
image-forming device, and photographic film or a silicon electronic image sensor is the
sensing medium. The respective recording medium can be the film itself, or a
digital electronic or magnetic memory.
Photographers
control the camera and lens to "expose" the light recording material
(such as film) to the required amount of light to form a "latent image" (on
film) or "raw file" (in digital cameras) which, after appropriate processing,
is converted to a usable image. Digital cameras use an electronic image sensor based on
light-sensitive electronics such as charge-coupled
device (CCD) or complementary metal-oxide-semiconductor (CMOS)
technology. The resulting digital image is stored electronically, but can be
reproduced on paper or film.
The movie camera is a type of
photographic camera which takes a rapid sequence of photographs on strips of
film. In contrast to a still camera, which captures a single snapshot at a
time, the movie camera takes a series of images, each called a
"frame". This is accomplished through an intermittent mechanism. The
frames are later played back in a movie projector at a specific speed, called
the "frame rate" (number of frames per second). While viewing, a
person's eyes and brain merge the separate pictures together to create the
illusion of motion.[2]
In all but
certain specialized cameras, the process of obtaining a usable exposure must
involve the use, manually or automatically, of a few controls to ensure the
photograph is clear, sharp and well illuminated. The controls usually include
but are not limited to the following:
Types of
digital cameras
Digital
cameras are made in a wide range of sizes, prices and capabilities. The
majority are camera phones, operated as
a mobile application through the
cellphone menu. Professional photographers and many amateurs use larger, more expensive
digital single-lens reflex
cameras (DSLR) for their greater versatility. Between these
extremes lie digital compact cameras and bridge digital cameras that
"bridge" the gap between amateur and professional cameras.
Specialized cameras including multispectral imaging equipment and
astrographs continue to serve the scientific, military,
medical and other special purposes for which digital photography was invented.
Control
|
Description
|
The
adjustment to place the sharpest focus where it is desired on the subject.
|
|
Adjustment
of the lens
opening, measured as f-number,
which controls the amount of light passing through the lens. Aperture also
has an effect on depth
of field and diffraction
– the higher the f-number, the smaller the opening, the less light, the
greater the depth of field, and the more the diffraction blur. The focal
length divided by the f-number gives the effective aperture diameter.
|
|
Adjustment
of the speed (often expressed either as fractions of seconds or as an angle,
with mechanical shutters) of the shutter to control the amount of time during
which the imaging medium is exposed to light for each exposure. Shutter speed
may be used to control the amount of light striking the image plane; 'faster'
shutter speeds (that is, those of shorter duration) decrease both the amount
of light and the amount of image blurring from motion of the subject and/or
camera.
|
|
On digital
cameras, electronic compensation for the color
temperature associated with a given set of lighting conditions,
ensuring that white light is registered as such on the imaging chip and
therefore that the colors in the frame will appear natural. On mechanical,
film-based cameras, this function is served by the operator's choice of film stock
or with color correction filters. In addition to using white balance to
register natural coloration of the image, photographers may employ white
balance to aesthetic end, for example white balancing to a blue object in
order to obtain a warm color
temperature.
|
|
Metering
|
Measurement
of exposure so that highlights and shadows are exposed according to the
photographer's wishes. Many modern cameras meter and set exposure automatically.
Before automatic exposure, correct exposure was accomplished with the use of
a separate light
metering device or by the photographer's knowledge and
experience of gauging correct settings. To translate the amount of light into
a usable aperture and shutter speed, the meter needs to adjust for the
sensitivity of the film or sensor to light. This is done by setting the
"film speed" or ISO sensitivity into the meter.
|
Traditionally
used to "tell the camera" the film speed
of the selected film on film cameras, ISO speeds are employed on modern
digital cameras as an indication of the system's gain
from light to numerical output and to control the automatic exposure system.
The higher the ISO number the greater the film sensitivity to light, whereas
with a lower ISO number, the film is less sensitive to light. A correct
combination of ISO speed, aperture, and shutter speed leads to an image that
is neither too dark nor too light, hence it is 'correctly exposed,' indicated
by a centered meter.
|
|
Autofocus
point
|
On some
cameras, the selection of a point in the imaging frame upon which the
auto-focus system will attempt to focus. Many Single-lens
reflex cameras (SLR) feature multiple auto-focus points
in the viewfinder.
|
Many other
elements of the imaging device itself may have a pronounced effect on the
quality and/or aesthetic effect of a given photograph; among them are:
- Focal length and type of lens (telephoto or "long" lens, macro, wide angle, fisheye, or zoom)
- Filters placed between the subject and the light recording material, either in front of or behind the lens
- Inherent sensitivity of the medium to light intensity and color/wavelengths.
- The nature of the light recording material, for example its resolution as measured in pixels or grains of silver halide.
Exposure and
rendering
Camera
controls are inter-related. The total amount of light reaching the film plane
(the "exposure") changes with the duration of exposure, aperture of
the lens, and on the effective focal length of the lens (which in variable
focal length lenses, can force a change in aperture as the lens is zoomed).
Changing any of these controls can alter the exposure. Many cameras may be set
to adjust most or all of these controls automatically. This automatic
functionality is useful for occasional photographers in many situations.
The duration
of an exposure is referred to as shutter speed, often even in cameras that
don't have a physical shutter, and is typically measured in fractions of a
second. Aperture is expressed by an f-number or f-stop (derived from focal
ratio), which is proportional to the ratio of the focal length to the diameter
of the aperture. If the f-number is decreased by a factor of 
, the
aperture diameter is increased by the same factor, and its area is increased by
a factor of 2. The f-stops that might be found on a typical lens include 2.8,
4, 5.6, 8, 11, 16, 22, 32, where going up "one stop" (using lower
f-stop numbers) doubles the amount of light reaching the film, and stopping down one stop
halves the amount of light.
, the
aperture diameter is increased by the same factor, and its area is increased by
a factor of 2. The f-stops that might be found on a typical lens include 2.8,
4, 5.6, 8, 11, 16, 22, 32, where going up "one stop" (using lower
f-stop numbers) doubles the amount of light reaching the film, and stopping down one stop
halves the amount of light.
Exposures can
be achieved through various combinations of shutter speed and aperture. For
example, f/8 at 8 ms (1/125th of a second) and f/5.6 at 4 ms (1/250th of a
second) yield the same amount of light. The chosen combination has an impact on
the final result. The aperture and focal length of the lens determine the depth of field, which refers
to the range of distances from the lens that will be in focus. A longer lens or
a wider aperture will result in "shallow" depth of field (i.e. only a
small plane of the image will be in sharp focus). This is often useful for
isolating subjects from backgrounds as in individual portraits or macro
photography. Conversely, a shorter lens, or a smaller aperture, will result in
more of the image being in focus. This is generally more desirable when
photographing landscapes or groups of people. With very small apertures, such
as pinholes, a wide range
of distance can be brought into focus, but sharpness is severely degraded by diffraction with such
small apertures. Generally, the highest degree of "sharpness" is
achieved at an aperture near the middle of a lens's range (for example, f/8 for
a lens with available apertures of f/2.8 to f/16). However, as lens technology
improves, lenses are becoming capable of making increasingly sharp images at
wider apertures.
Digital
photography
Traditional
photography burdened photographers working at
remote locations without easy access to processing facilities, and competition
from television pressured photographers to deliver images to newspapers with
greater speed. Photo journalists at remote locations often carried miniature
photo labs and a means of transmitting images through telephone lines Digital
imaging uses an electronic image sensor to record the
image as a set of electronic data rather than as chemical changes on film. The
primary difference between digital and chemical photography is that chemical
photography resists manipulation because it involves film and photographic
paper, while digital imaging is a highly manipulative medium.
This difference allows for a degree of image post-processing that is
comparatively difficult in film-based photography and permits different
communicative potentials and applications.
Depth of field
In optics, particularly as it relates to film and photography, the depth of field (DOF) is
the portion of a scene that appears acceptably sharp in the image. Although a lens can precisely focus at only one distance, the
decrease in sharpness is gradual on each side of the focused distance, so that
within the DOF, the unsharpness is imperceptible under normal viewing
conditions.
In some cases,
it may be desirable to have the entire image sharp, and a large DOF is
appropriate. In other cases, a small DOF may be more effective, emphasizing the
subject while de-emphasizing the foreground and background. In cinematography, a large DOF is often called deep focus, and a small DOF is often called shallow focus.
The DOF is
determined by the subject distance (that is, the distance to the plane that is
perfectly in focus), the lens focal length, the lens f-number, and the format
size or circle
of confusion
criterion.
For a given
format size, at moderate subject distances, DOF is approximately determined by
the subject magnification and the lens f-number. For a
given f-number, increasing the magnification, either by moving closer to
the subject or using a lens of greater focal length, decreases the DOF;
decreasing magnification increases DOF. For a given subject magnification,
increasing the f-number (decreasing the aperture diameter) increases the
DOF; decreasing f-number decreases DOF.
When a picture
is taken in two different format sizes from the same distance at the same f-number
with lenses that give the same angle of view, the smaller format has greater
DOF. When a picture is taken in two different formats from the same distance at
the same f-number using lenses of the same focal length, the
smaller format has less DOF.
Cropping an
image and enlarging to the same size final image as an uncropped image taken
under the same conditions is equivalent to using a smaller format under the
same conditions, so the cropped image has less DOF.
When focus is
set to the hyperfocal
distance, the DOF
extends from half the hyperfocal distance to infinity, and the DOF is the
largest possible for a given f-number.
The advent of
digital technology in photography has provided additional means of controlling
the extent of image sharpness; some methods allow extended DOF that would be
impossible with traditional techniques, and some allow the DOF to be determined
after the image is made
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