Other Photographic Techniques
Stereoscopic
Main article: Stereoscopy
Photographs, both monochrome and color, can be captured and
displayed through two side-by-side images that emulate human stereoscopic
vision. While known colloquially as "3-D" photography, the more
accurate term is stereoscopy. Such cameras have long been realized by using
film, and more recently in digital electronic methods (including cellphone
cameras).
Full-spectrum, ultraviolet and infrared[edit]
This image of the rings of Saturn is an example of the
application of ultraviolet photography in astronomy
Main article: Full spectrum photography
Ultraviolet and infrared films have been available for many
decades and employed in a variety of photographic avenues since the 1960s. New
technological trends in digital photography have opened a new direction in full
spectrum photography, where careful filtering choices across the ultraviolet,
visible and infrared lead to new artistic visions.
Modified digital cameras can detect some ultraviolet, all of
the visible and much of the near infrared spectrum, as most digital imaging
sensors are sensitive from about 350 nm to 1000 nm. An off-the-shelf digital
camera contains an infrared hot mirror filter that blocks most of the infrared
and a bit of the ultraviolet that would otherwise be detected by the sensor,
narrowing the accepted range from about 400 nm to 700 nm.
Replacing a hot mirror or infrared blocking filter with an
infrared pass or a wide spectrally transmitting filter allows the camera to
detect the wider spectrum light at greater sensitivity. Without the hot-mirror,
the red, green and blue (or cyan, yellow and magenta) colored micro-filters
placed over the sensor elements pass varying amounts of ultraviolet (blue
window) and infrared (primarily red and somewhat lesser the green and blue
micro-filters).
Uses of full spectrum photography are for fine art
photography, geology, forensics and law enforcement.
"Light field photography"
Digital methods of image capture and display processing have
enabled the new technology of "light field photography" (also known
as synthetic aperture photography). This process allows focusing at various
depths of field to be selected after the photograph has been captured. As
explained by Michael Faraday in 1846, the "light field" is understood
as 5-dimensional, with each point in 3-d space having attributes of two more
angles that define the direction of each ray passing through that point.
These additional vector attributes can be captured optically
through the use of microlenses at each pixel-point within the 2-dimensional
image sensor. Every pixel of the final image is actually a selection from each
sub-array located under each microlens, as identified by a post-image capture
focus algorithm.Exposure and rendering
Camera controls are interrelated. 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 do not have a physical shutter, and is typically
measured in fractions of a second. It is quite possible to have exposures from
one up to several seconds, usually for still-life subjects, and for night
scenes exposure times can be several hours.
The effective 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. Longer lenses will pass less light even
though the diameter of the aperture is the same due to the greater distance the
light has to travel; shorter lenses (a shorter focal length) will be brighter
with the same size of aperture.
The smaller the f/number, the larger the effective aperture.
The present system of f/numbers to give the effective aperture of a lens was
standardized by an international convention. There were earlier, different
series of numbers in older cameras.
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.
Image capture can be achieved through various combinations
of shutter speed, aperture, and film or sensor speed. Different (but related)
settings of aperture and shutter speed enable photographs to be taken under
various conditions of film or sensor speed, lighting and motion of subjects
and/or camera, and desired depth of field. A slower speed film will exhibit
less "grain", and a slower speed setting on an electronic sensor will
exhibit less "noise", while higher film and sensor speeds allow for a
faster shutter speed, which reduces motion blur or allows the use of a smaller
aperture to increase the depth of field.
For example, a wider aperture is used for lower light and a
lower aperture for more light. If a subject is in motion, then a high shutter
speed may be needed. A tripod can also be helpful in that it enables a slower
shutter speed to be used.
For example, f/8 at 8 ms (1/125 of a second) and f/5.6 at 4
ms (1/250 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.
Image capture is only part of the image forming process.
Regardless of material, some process must be employed to render the latent
image captured by the camera into a viewable image. With slide film, the
developed film is just mounted for projection. Print film requires the
developed film negative to be printed onto photographic paper or transparency.
Digital images may be uploaded to an image server (e.g., a photo-sharing web
site), viewed on a television, or transferred to a computer or digital photo
frame. Every type can be printed on more "classical" mediums such as
regular paper or photographic paper for examples.
A photographer using a tripod for greater stability during
long exposure.
Prior to the rendering of a viewable image, modifications
can be made using several controls. Many of these controls are similar to
controls during image capture, while some are exclusive to the rendering
process. Most printing controls have equivalent digital concepts, but some
create different effects. For example, dodging and burning controls are
different between digital and film processes. Other printing modifications
include:
Chemicals and process used during film development
Duration of print exposure – equivalent to shutter speed
Printing aperture – equivalent to aperture, but has no
effect on depth of field
Contrast – changing the visual properties of objects in an
image to make them distinguishable from other objects and the background
Dodging – reduces exposure of certain print areas, resulting
in lighter areas
Burning in – increases exposure of certain areas, resulting
in darker areas
Paper texture – glossy, matte, etc.
Paper type – resin-coated (RC) or fiber-based (FB)
Paper size
Exposure Shape — resulting prints in shapes such as
circular, oval, loupe, etc.
Toners – used to add warm or cold tones to black-and-white
printsExposure and rendering
Camera controls are interrelated. 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 do not have a physical shutter, and is typically
measured in fractions of a second. It is quite possible to have exposures from
one up to several seconds, usually for still-life subjects, and for night
scenes exposure times can be several hours.
The effective 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. Longer lenses will pass less light even
though the diameter of the aperture is the same due to the greater distance the
light has to travel; shorter lenses (a shorter focal length) will be brighter
with the same size of aperture.
The smaller the f/number, the larger the effective aperture.
The present system of f/numbers to give the effective aperture of a lens was
standardized by an international convention. There were earlier, different
series of numbers in older cameras.
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.
Image capture can be achieved through various combinations
of shutter speed, aperture, and film or sensor speed. Different (but related)
settings of aperture and shutter speed enable photographs to be taken under
various conditions of film or sensor speed, lighting and motion of subjects
and/or camera, and desired depth of field. A slower speed film will exhibit
less "grain", and a slower speed setting on an electronic sensor will
exhibit less "noise", while higher film and sensor speeds allow for a
faster shutter speed, which reduces motion blur or allows the use of a smaller
aperture to increase the depth of field.
For example, a wider aperture is used for lower light and a
lower aperture for more light. If a subject is in motion, then a high shutter
speed may be needed. A tripod can also be helpful in that it enables a slower
shutter speed to be used.
For example, f/8 at 8 ms (1/125 of a second) and f/5.6 at 4
ms (1/250 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.
Image capture is only part of the image forming process.
Regardless of material, some process must be employed to render the latent
image captured by the camera into a viewable image. With slide film, the
developed film is just mounted for projection. Print film requires the
developed film negative to be printed onto photographic paper or transparency.
Digital images may be uploaded to an image server (e.g., a photo-sharing web
site), viewed on a television, or transferred to a computer or digital photo
frame. Every type can be printed on more "classical" mediums such as
regular paper or photographic paper for examples.
A photographer using a tripod for greater stability during
long exposure.
Prior to the rendering of a viewable image, modifications
can be made using several controls. Many of these controls are similar to
controls during image capture, while some are exclusive to the rendering
process. Most printing controls have equivalent digital concepts, but some
create different effects. For example, dodging and burning controls are
different between digital and film processes. Other printing modifications
include:
Chemicals and process used during film development
Duration of print exposure – equivalent to shutter speed
Printing aperture – equivalent to aperture, but has no
effect on depth of field
Contrast – changing the visual properties of objects in an
image to make them distinguishable from other objects and the background
Dodging – reduces exposure of certain print areas, resulting
in lighter areas
Burning in – increases exposure of certain areas, resulting
in darker areas
Paper texture – glossy, matte, etc.
Paper type – resin-coated (RC) or fiber-based (FB)
Paper size
Exposure Shape — resulting prints in shapes such as
circular, oval, loupe, etc.
Toners – used to add warm or cold tones to black-and-white
prints
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