photography Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is emplo ...

, backscatter (also called near-camera reflection) is an

optical phenomenon Optical phenomena are any observable events that result from the interaction of light and matter. All optical phenomena coincide with quantum phenomena. Common optical phenomena are often due to the interaction of light from the sun or moon wit ...

resulting in typically circular artifacts on an image, due to the camera's flash being reflected from unfocused motes of

dust Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in ...

, water droplets, or other

particle In the physical sciences, a particle (or corpuscule in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from ...

s in the

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

or water. It is especially common with modern compact and ultra-compact digital cameras. Orb photographic

Caused by the

backscatter In physics, backscatter (or backscattering) 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, a ...

of light by unfocused particles, these artifacts are also sometimes called orbs, referring to a common

paranormal Paranormal events are purported phenomena described in popular culture, folk, and other non-scientific bodies of knowledge, whose existence within these contexts is described as being beyond the scope of normal scientific understanding. Not ...

claim. Some appear with trails, suggesting

motion In physics, motion is the phenomenon in which an object changes its position with respect to time. Motion is mathematically described in terms of displacement, distance, velocity, acceleration, speed and frame of reference to an observer and m ...

Cause

Backscatter commonly occurs in low-light scenes when the camera's flash is used. Cases include

nighttime Night (also described as night time, unconventionally spelled as "nite") is the period of ambient darkness from sunset to sunrise during each 24-hour day, when the Sun is below the horizon. The exact time when night begins and ends depends on ...

and

underwater photography 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 ...

, when a bright light source and reflective unfocused particles are near the camera. Light appears much brighter very near the source due to the

inverse-square law In science, an inverse-square law is any scientific law stating that a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be unders ...

, which says light intensity is inversely proportional to the square of the distance from the source.Richard Ferncase.
Basic Lighting Worktext for Film and Video
'. CRC Press; 1992. . p. 66. The artifact can result from the

retroreflection A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects radiation (usually light) back to its source with minimum scattering. This works at a wide range of angle of incidence, unlike a planar mirror, ...

of the light from

airborne Airborne or Airborn may refer to: Arts, entertainment, and media Films * ''Airborne'' (1962 film), a 1962 American film directed by James Landis * ''Airborne'' (1993 film), a comedy–drama film * ''Airborne'' (1998 film), an action film sta ...

solid particles, such as

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

, or liquid droplets, especially

rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

mist Mist is a phenomenon caused by small droplets of water suspended in the cold air, usually by condensation. Physically, it is an example of a dispersion. It is most commonly seen where water vapor in warm, moist air meets sudden cooling, such a ...

. They can also be caused by foreign material within the camera lens. The image artifacts usually appear as either white or semi- transparent circles, though may also occur with whole or partial color spectra,

purple fringing In photography (particularly digital photography), purple fringing (sometimes called PF) is the term for an unfocused purple or magenta "ghost" image on a photograph. This optical aberration is generally most visible as a coloring and lightening ...

or other

chromatic aberration In optics, chromatic aberration (CA), also called chromatic distortion and spherochromatism, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the w ...

. With rain droplets, an image may capture light passing through the droplet creating a small rainbow effect.J. David Pye.
Polarised Light in Science and Nature
'. CRC Press; 2015. . p. 81.

Fujifilm , trading as Fujifilm, or simply Fuji, is a Japanese multinational conglomerate headquartered in Tokyo, Japan, operating in the realms of photography, optics, office and medical electronics, biotechnology, and chemicals. The offerings from the ...

describes the artifacts as a common photographic problem: Photographical orbs

In underwater scenes, particles such as sand or

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

marine life Marine life, sea life, or ocean life is the plants, animals and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. ...

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.Nick Robertson-Brown.
Underwater Photography: Art and Techniques
'. Crowood; 31 January 2014. . p. 105. The effect is also seen on infrared video cameras, where superbright infrared LEDs illuminate

microscopic The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...

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 The Angle (Bloody Angle colloq.) is a Gettysburg Battlefield area which includes the 1863 Copse of Trees used as the target landmark for Pickett's Charge, the 1892 monument that marks the high-water mark of the Confederacy, a rock wall, and sev ...

of light

reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...

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.

Paranormal claims

Some ghost hunters have claimed that orb shaped visual artifacts appearing in photographs are spirits of the dead. Others have claimed that orbs are an unknown sort of being, based partly on perceived intent in the orbs' movements. Such perceptions have been interpreted by

Michael Shermer Michael Brant Shermer (born September 8, 1954) is an American science writer, historian of science, executive director of The Skeptics Society, and founding publisher of ''Skeptic'' magazine, a publication focused on investigating pseudoscientifi ...

as examples of agenticity. Prominent paranormal investigators such as

Joe Nickell Joe Nickell (born December 1, 1944) is an American skeptic and investigator of the paranormal. Nickell is senior research fellow for the Committee for Skeptical Inquiry and writes regularly for their journal, ''Skeptical Inquirer''. He is also ...

have agreed with skeptic-debunkers' assessments that orbs result from natural phenomena like insects, dust, pollen, or water droplets.Joe Nickell.. p. 159.

References

External links

{{Parapsychology Digital photography Paranormal Science of photography

Cause

Paranormal claims

See also

References

External links