In photography, backscatter (also called near-camera reflection [1] ) is an optical phenomenon resulting in typically circular artifacts on an image, due to the camera's flash being reflected from unfocused motes of dust, water droplets, or other particles in the air or water. It is especially common with modern compact and ultra-compact digital cameras. [2] [3]
Caused by the backscatter of light by unfocused particles, these artifacts are also sometimes called orbs, referring to a common paranormal claim. Some appear with trails, suggesting motion. [4]
Backscatter commonly occurs in low-light scenes when the camera's flash is used. Cases include nighttime and underwater photography, when a bright light source and reflective unfocused particles are near the camera. [1] Light appears much brighter very near the source due to the inverse-square law, which says light intensity is inversely proportional to the square of the distance from the source. [5]
The artifact can result from the backscatter or retroreflection of the light from airborne solid particles, such as dust or pollen, or liquid droplets, especially rain or mist. They can also be caused by foreign material within the camera lens. [2] [4] The image artifacts usually appear as either white or semi-transparent circles, though may also occur with whole or partial color spectra, purple fringing or other chromatic aberration. With rain droplets, an image may capture light passing through the droplet creating a small rainbow effect. [6]
Fujifilm describes the artifacts as a common photographic problem:
There is always a certain amount of dust floating around in the air. You may have noticed this at the movies when you look up at the light coming from the movie projector and notice the bright sparks floating around in the beam. In the same way, there are always dust particles floating around nearby when you take pictures with your camera. When you use the flash, the light from the flash reflects off the dust particles and is sometimes captured in your shot. Of course, dust particles very close to the camera are blurred since they are not in focus, but because they reflect the light more strongly than the more distant main subject of the shot, that reflected light can sometimes be captured by the camera and recorded on the resulting image as round white spots. So these dots are the blurred images of dust particles. [2]
In underwater scenes, particles such as sand or planktonic marine life near the lens, invisible to the diver, reflect light from the flash causing the orb artifact in the image. A strobe flash, which distances the flash from the lens, eliminates the artifacts. [7] The effect is also seen on infrared video cameras, where superbright infrared LEDs illuminate microscopic particles very close to the lens. The artifacts are especially common with compact or ultra-compact cameras, where the short distance between the lens and the built-in flash decreases the angle of light reflection toward the lens, directly illuminating the aspect of the particles facing the lens and increasing the camera's ability to capture the light reflected from normally subvisible particles. [2]
Some ghost hunters have claimed that orb shaped visual artifacts appearing in photographs are spirits of the dead. [8] [9] Such perceptions have been interpreted by Michael Shermer as examples of agenticity. [10] Prominent paranormal investigators such as Joe Nickell have agreed with skeptic-debunkers' assessments that orbs result from natural phenomena like insects, dust, pollen, or water droplets. [11] [12]
A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured.
A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.
A digital camera, also called a digicam, is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Digital cameras are now widely incorporated into mobile devices like smartphones with the same or more capabilities and features of dedicated cameras. High-end, high-definition dedicated cameras are still commonly used by professionals and those who desire to take higher-quality photographs.
A flash is a device used in photography that produces a brief burst of light at a color temperature of about 5500 K to help illuminate a scene. The main purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically.
Underwater photography is the process of taking photographs while under water. It is usually done while scuba diving, but can be done while diving on surface supply, snorkeling, swimming, from a submersible or remotely operated underwater vehicle, or from automated cameras lowered from the surface.
In physics, backscatter is the reflection of waves, particles, or signals back to the direction from which they came. It is usually a diffuse reflection due to scattering, as opposed to specular reflection as from a mirror, although specular backscattering can occur at normal incidence with a surface. Backscattering has important applications in astronomy, photography, and medical ultrasonography. The opposite effect is forward scatter, e.g. when a translucent material like a cloud diffuses sunlight, giving soft light.
Macro photography is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is greater than life-size . By the original definition, a macro photograph is one in which the size of the subject on the negative or image sensor is life-size or greater. In some senses, however, it refers to a finished photograph of a subject that is greater than life-size.
A point-and-shoot camera, also known as a compact camera and sometimes abbreviated to P&S, is a still camera designed primarily for simple operation. Most use focus free lenses or autofocus for focusing, automatic systems for setting the exposure options, and have flash units built in. They are popular for vernacular photography by people who do not consider themselves photographers but want easy-to-use cameras for snapshots of vacations, parties, reunions and other events.
A digital single-lens reflex camera is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor.
Spirit photography is a type of photography whose primary goal is to capture images of ghosts and other spiritual entities, especially in ghost hunting. It dates back to the late 19th century. The end of the American Civil War and the mid-19th Century Spiritualism movement contributed greatly to the popularity of spirit photography. The omnipresence of death in the Victorian period created a desire for evidence of the afterlife, and those who partook in Spirit Photography oftentimes hoped to receive images that depicted the likeness of a deceased relative or loved one. Photographers such as William Mumler and William Hope ran thriving businesses taking photos of people with their supposed dead relatives. Both were shown to be frauds, but "true believers", such as Sir Arthur Conan Doyle, refused to accept the evidence as proof of a hoax.
Ultraviolet photography is a photographic process of recording images by using radiation from the ultraviolet (UV) spectrum only. Images taken with ultraviolet radiation serve a number of scientific, medical or artistic purposes. Images may reveal deterioration of art works or structures not apparent under light. Diagnostic medical images may be used to detect certain skin disorders or as evidence of injury. Some animals, particularly insects, use ultraviolet wavelengths for vision; ultraviolet photography can help investigate the markings of plants that attract insects, while invisible to the unaided human eye. Ultraviolet photography of archaeological sites may reveal artifacts or traffic patterns not otherwise visible.
Ghost hunting is the process of investigating locations that are purportedly haunted by ghosts. The practice has been heavily criticized for its dismissal of the scientific method. No scientific study has ever been able to confirm the existence of ghosts. Ghost hunting is considered a pseudoscience by the vast majority of educators, academics, science writers and skeptics. Science historian Brian Regal described ghost hunting as "an unorganized exercise in futility".
The following outline is provided as an overview of and topical guide to photography:
The Sigma SD14 is a digital single-lens reflex camera produced by the Sigma Corporation of Japan. It is fitted with a Sigma SA mount which takes Sigma SA lenses.
The Fujifilm FinePix products are a line of digital cameras produced by Fujifilm. They include compact point and shoot models, tough, waterproof models, bridge digital cameras, digital SLRs and mirrorless cameras. Many use Fujifilm's proprietary Super CCD technology sensors and CMOS sensors for high-end models.
Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, and resolution of the film. Film is typically segmented in frames, that give rise to separate photographs.
Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of atmospheric processes .... [including] temporal and spatial resolutions beyond those discernible with the naked eye". Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". Nevertheless, the two terms are sometimes used interchangeably.
The Fujifilm X series is a line of digital cameras produced by Fujifilm. The series encompasses fixed lens and interchangeable lens mirrorless cameras and premium compact point-and-shoot cameras aimed at consumer, enthusiast and professional photographers. The X series is part of the larger FinePix range of digital cameras from Fujifilm.
The Fujifilm X-T1 is a weather-resistant mirrorless interchangeable lens camera announced by Fujifilm on January 28, 2014. It uses the Fujifilm X-mount and is the first entry in the X-T lineage of DSLR-styled X series cameras.
The Fujifilm X10 is a 2/3 sensor digital compact camera announced by Fujifilm on September 1, 2011. At the time of its release, it competed most closely with the Panasonic Lumix DMC-LX5, Olympus XZ-1, Canon PowerShot G1 X and Sony Cyber-shot DSC-RX100, and was subsequently named a 2013 iF product design award recipient.
An additional problem called backscatter occurs when flash light striking these suspended particles reflects back to the camera lens and records on the film as fuzzy white spots. Of course, backscatter can also be reduced by getting the camera as close to your subjects as possible, because the shorter that distance, the fewer the number of floating particles in front of the lens.
Media related to Photographical orbs at Wikimedia Commons