Full spectrum photography
Encyclopedia
Full-spectrum photography is a subset of full spectral imaging
, defined currently among photography enthusiasts as imaging with consumer cameras the full, broad spectrum of a film or camera sensor bandwidth. In practice, specialized broadband/full-spectrum film captures visible and near infrared
light, commonly referred to as the "VNIR
".
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 350nm to 1000nm. 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 400nm to 700nm. 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) elements of the color filter array
placed over the sensor elements pass varying amounts of ultraviolet (blue window) and infrared (primarily red, and somewhat lesser the green and blue filters). A converted full-spectrum camera can be used for ultraviolet photography
or infrared photography
with the appropriate filters.
Uses of full-spectrum photography include fine art photography
, geology, forensics
& law enforcement, and even some claimed use in ghost hunting
.
, both multispectral and hyperspectral imaging
, which began as early as the late 1950s and early 1960s as means for geological and military remote sensing
. Wideband panchromatic film has been available in various forms since the 1920s, when some UV and IR sensitivity remained in commercially available emulsions. The earliest color films sometimes included wider band color than recent commercial emulsions, and can be recognized by the more reddish and or limited color tones of early color prints (not to be confused with print fading).
In the late 1990s enthusiastic photographers began shooting infrared with digital cameras, necessitating either long exposures or the removal of the internal hot mirror. Most replaced the hot mirror with an infrared pass filter of the same optical thickness (to retain focus) and pass only infrared light to achieve results seen with infrared B&W film. Around 2000, electro-optical engineer David Twede, already engaged in VNIR and infrared spectral remote sensing, ventured into Full-spectrum photography art, using a modified digital camera to explore broader spectral imaging and developing art around it. Around 2003, forensics photographers
using engineered cameras for specific purposes began modifying off-the-shelf digital camera
s to acquire less expensive tools. And most recently, Full-spectrum photography is being used by enthusiasts of ghost hunting
, though no claims of actually photographing psychic phenomenon
with Full-spectrum or infrared photography have been substantiated.
Today, there are a few places that will modify digital cameras to pass broad, full-spectrum light for full spectral imaging. A few DSLR cameras such as the Fujifilm FinePix IS Pro
are purpose-designed for full spectrum use and respond from approximately 1000nm (IR) to 380nm (UV).
s can be made to record non-visible ultraviolet (UV) and infrared (IR) radiation. In each case, they generally require special equipment: converted digital cameras, specific filters, highly transmitting lenses, etc. For example, most photographic lenses are made of glass and will filter out most ultraviolet light. Instead, expensive lenses made of quartz must be used. Infrared films may be shot in standard cameras using an infrared pass filters, although focus must compensate for the infrared focal point.
A converted digital camera usually requires that the infrared hot mirror be removed and replaced by a wideband, spectrally flat glass of the same optical path length
. Typical glass types used include Schott WG-280 and BK-7, which transmit as much as 90% from around 300nm to past 1000nm. Removing the hot mirror is tedious and may require special tools and clean rooms.
Once the camera is sensitive to the full-spectrum, external filters can be used to selectively filter portions of the UV, visible and infrared to achieve various effects. For example, a standard red #25a can be used to include red light and infrared light together, yielding particularly strong two-toned color images of a reddish nature except where the infrared is high and shows as cyan. Another example, using UV/IR filters such as the 18A or U-330 yield a two or three toned image in which blues and yellows dominate. Less common filters have been claimed to give a variety of color effects ranging from diverse pastel foliage and deep blue skies to surrealistic effects of the sky and ground, though digital image processing
is likely required to achieve the full effects. One issue with Full-spectrum on converted digital cameras is the chromatic aberration
of the wideband information. That is, different colors, including the ultraviolet and infrared, will focus at different focal points, yielding blurry images and color edge effects, depending on the focal length used.
Full-spectrum photography achieves various effects and surrealistic colors from the interaction of reflectivity (UV, visible, IR) of nature and manmade materials and the specific spectral transmission of the red, green and blue filters on the camera. The addition of external filters will reduce and emphasize different interactions, yielding different effects.
. Most full-spectrum art is of landscapes. A movement is also building for artistic human photography with Full-spectrum photography, that captures a real person interacting with a surreal landscape. Full-spectrum photography art is currently displayed at galleries in Colorado and Florida.
/mineralogy
, agriculture
and oceanographic purposes. Most consumer cameras retain the red, green and blue micro-filters, thus limiting their usefulness in scientific imaging.
often uses Full-spectrum cameras to emphasize non-visible materials which have more diverse reflectivities in the ultraviolet and infrared. Applications include non-visible inks (uv & ir), disturbed soil (uv & ir), gunshot residue (ir), body fluids (uv), fibers, etc. Analogous to forensics, Full-spectrum cameras are being explored to enhance photographic recordings of archeological findings.
Full Spectral Imaging
Full spectral imaging is a form of Imaging spectroscopy and is the successor to Hyperspectral imaging. Full Spectral Imaging was developed to improve the capabilities of Earth remote sensing . Hyperspectral imaging acquires data as many contiguous spectral bands. Full Spectral Imaging acquires...
, defined currently among photography enthusiasts as imaging with consumer cameras the full, broad spectrum of a film or camera sensor bandwidth. In practice, specialized broadband/full-spectrum film captures visible and near infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
light, commonly referred to as the "VNIR
VNIR
VNIR is an initialism for visible and near-infrared, a portion of the electromagnetic spectrum having wavelengths between approximately 400 and 1400 nanometers ...
".
Modified digital cameras can detect some ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
, all of the visible and much of the near infrared spectrum, as most digital imaging sensors are sensitive from about 350nm to 1000nm. An off-the-shelf digital camera contains an infrared hot mirror
Hot mirror
A hot mirror is a specialized dielectric mirror, a dichroic filter, often employed to protect optical systems by reflecting infrared light back into a light source, while allowing visible light to pass...
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 400nm to 700nm. 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) elements of the color filter array
Color filter array
In photography, a color filter array , or color filter mosaic , is a mosaic of tiny color filters placed over the pixel sensors of an image sensor to capture color information....
placed over the sensor elements pass varying amounts of ultraviolet (blue window) and infrared (primarily red, and somewhat lesser the green and blue filters). A converted full-spectrum camera can be used for ultraviolet photography
Ultraviolet photography
Ultraviolet photography is a photographic process of recording images by using light from the ultraviolet spectrum only.-Overview:Light which is visible to the human eye covers the spectral region from about 400 to 750 nanometers. This is the radiation spectrum used in normal photography...
or infrared photography
Infrared photography
In infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about...
with the appropriate filters.
Uses of full-spectrum photography include fine art photography
Fine art photography
Fine art photography refers to photographs that are created in accordance with the creative vision of the photographer as artist. Fine art photography stands in contrast to photojournalism, which provides a visual account for news events, and commercial photography, the primary focus of which is to...
, geology, forensics
History of forensic photography
Forensic science holds the branch of Forensic photography which encompasses documenting both suspected and convicted criminals, and also the crime scenes, victims, and other evidence needed to make a conviction...
& law enforcement, and even some claimed use in ghost hunting
Ghost hunting
Ghost Hunting is the process of investigating locations that are reported to be haunted by ghosts.Typically, a ghost hunting team will attempt to collect evidence claimed to be supportive of paranormal activity...
.
History
Full-spectrum photography has its roots in spectral imagingSpectral imaging
Spectral imaging is a branch of spectroscopy and of photography in which a complete spectrum or some spectral information is collected at every location in an image plane...
, both multispectral and hyperspectral imaging
Hyperspectral imaging
Hyperspectral imaging collects and processes information from across the electromagnetic spectrum. Much as the human eye sees visible light in three bands , spectral imaging divides the spectrum into many more bands...
, which began as early as the late 1950s and early 1960s as means for geological and military remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
. Wideband panchromatic film has been available in various forms since the 1920s, when some UV and IR sensitivity remained in commercially available emulsions. The earliest color films sometimes included wider band color than recent commercial emulsions, and can be recognized by the more reddish and or limited color tones of early color prints (not to be confused with print fading).
In the late 1990s enthusiastic photographers began shooting infrared with digital cameras, necessitating either long exposures or the removal of the internal hot mirror. Most replaced the hot mirror with an infrared pass filter of the same optical thickness (to retain focus) and pass only infrared light to achieve results seen with infrared B&W film. Around 2000, electro-optical engineer David Twede, already engaged in VNIR and infrared spectral remote sensing, ventured into Full-spectrum photography art, using a modified digital camera to explore broader spectral imaging and developing art around it. Around 2003, forensics photographers
Forensic photography
Forensic photography, sometimes referred to as forensic imaging or crime scene photography, is the art of producing an accurate reproduction of a crime scene or an accident scene using photography for the benefit of a court or to aid in an investigation. It is part of the process of evidence...
using engineered cameras for specific purposes began modifying off-the-shelf digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
s to acquire less expensive tools. And most recently, Full-spectrum photography is being used by enthusiasts of ghost hunting
Ghost hunting
Ghost Hunting is the process of investigating locations that are reported to be haunted by ghosts.Typically, a ghost hunting team will attempt to collect evidence claimed to be supportive of paranormal activity...
, though no claims of actually photographing psychic phenomenon
Psychosis
Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...
with Full-spectrum or infrared photography have been substantiated.
Today, there are a few places that will modify digital cameras to pass broad, full-spectrum light for full spectral imaging. A few DSLR cameras such as the Fujifilm FinePix IS Pro
FinePix IS Pro
The FinePix IS Pro is a digital single lens reflex camera introduced by Fujifilm in 2007. It is based on a FinePix S5 Pro, which is in turn based on the Nikon D200. It has a Nikon F lens mount and can use most lenses made for 35 mm Nikon SLR cameras. It replaces the Fujifilm FinePix S3 Pro...
are purpose-designed for full spectrum use and respond from approximately 1000nm (IR) to 380nm (UV).
Basics
Digital sensors and photographic filmPhotographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...
s can be made to record non-visible ultraviolet (UV) and infrared (IR) radiation. In each case, they generally require special equipment: converted digital cameras, specific filters, highly transmitting lenses, etc. For example, most photographic lenses are made of glass and will filter out most ultraviolet light. Instead, expensive lenses made of quartz must be used. Infrared films may be shot in standard cameras using an infrared pass filters, although focus must compensate for the infrared focal point.
A converted digital camera usually requires that the infrared hot mirror be removed and replaced by a wideband, spectrally flat glass of the same optical path length
Optical path length
In optics, optical path length or optical distance is the product of the geometric length of the path light follows through the system, and the index of refraction of the medium through which it propagates. A difference in optical path length between two paths is often called the optical path...
. Typical glass types used include Schott WG-280 and BK-7, which transmit as much as 90% from around 300nm to past 1000nm. Removing the hot mirror is tedious and may require special tools and clean rooms.
Once the camera is sensitive to the full-spectrum, external filters can be used to selectively filter portions of the UV, visible and infrared to achieve various effects. For example, a standard red #25a can be used to include red light and infrared light together, yielding particularly strong two-toned color images of a reddish nature except where the infrared is high and shows as cyan. Another example, using UV/IR filters such as the 18A or U-330 yield a two or three toned image in which blues and yellows dominate. Less common filters have been claimed to give a variety of color effects ranging from diverse pastel foliage and deep blue skies to surrealistic effects of the sky and ground, though digital image processing
Digital image processing
Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing...
is likely required to achieve the full effects. One issue with Full-spectrum on converted digital cameras is the chromatic aberration
Chromatic aberration
In optics, chromatic aberration is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. It occurs because lenses have a different refractive index for different wavelengths of light...
of the wideband information. That is, different colors, including the ultraviolet and infrared, will focus at different focal points, yielding blurry images and color edge effects, depending on the focal length used.
Full-spectrum photography achieves various effects and surrealistic colors from the interaction of reflectivity (UV, visible, IR) of nature and manmade materials and the specific spectral transmission of the red, green and blue filters on the camera. The addition of external filters will reduce and emphasize different interactions, yielding different effects.
Art
Full-spectrum Photography is being used for art photography and can yield colors similar to visible color film, but with a brightness and tonality of infrared photographsInfrared photography
In infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about...
. Most full-spectrum art is of landscapes. A movement is also building for artistic human photography with Full-spectrum photography, that captures a real person interacting with a surreal landscape. Full-spectrum photography art is currently displayed at galleries in Colorado and Florida.
Science hobbyists
Hyperspectral and most multispectral cameras are expensive and difficult to operate, requiring a computer acquisition and laborious post-processing. Modified digital cameras with the proper filtering avail some limited spectral sensing for geologyGeology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
/mineralogy
Mineralogy
Mineralogy is the study of chemistry, crystal structure, and physical properties of minerals. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization.-History:Early writing...
, agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
and oceanographic purposes. Most consumer cameras retain the red, green and blue micro-filters, thus limiting their usefulness in scientific imaging.
Forensics
Forensics imagingHistory of forensic photography
Forensic science holds the branch of Forensic photography which encompasses documenting both suspected and convicted criminals, and also the crime scenes, victims, and other evidence needed to make a conviction...
often uses Full-spectrum cameras to emphasize non-visible materials which have more diverse reflectivities in the ultraviolet and infrared. Applications include non-visible inks (uv & ir), disturbed soil (uv & ir), gunshot residue (ir), body fluids (uv), fibers, etc. Analogous to forensics, Full-spectrum cameras are being explored to enhance photographic recordings of archeological findings.
See also
- Infrared photographyInfrared photographyIn infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about...
- Ultraviolet photographyUltraviolet photographyUltraviolet photography is a photographic process of recording images by using light from the ultraviolet spectrum only.-Overview:Light which is visible to the human eye covers the spectral region from about 400 to 750 nanometers. This is the radiation spectrum used in normal photography...
- Hyperspectral imagingHyperspectral imagingHyperspectral imaging collects and processes information from across the electromagnetic spectrum. Much as the human eye sees visible light in three bands , spectral imaging divides the spectrum into many more bands...
- Multispectral imaging
- Full-spectrum light
- History of forensic photographyHistory of forensic photographyForensic science holds the branch of Forensic photography which encompasses documenting both suspected and convicted criminals, and also the crime scenes, victims, and other evidence needed to make a conviction...
- Fujifilm FinePix IS Pro full spectrum cameraFinePix IS ProThe FinePix IS Pro is a digital single lens reflex camera introduced by Fujifilm in 2007. It is based on a FinePix S5 Pro, which is in turn based on the Nikon D200. It has a Nikon F lens mount and can use most lenses made for 35 mm Nikon SLR cameras. It replaces the Fujifilm FinePix S3 Pro...
External links
- Artistic full-spectrum photography
- More details about full-spectrum photography
- Forensics full-spectrum photography
- UV & IR photography
- Scientific hobbyists full-spectrum imaging
- The infrared and full-spectrum photography forum
- Human subject/model full-spectrum photography
- Near-UV to Near-IR kite aerial photography
- Flickr group dedicated to Fujifilm IS Pro, with sample UV and IR photos