Invention of pinhole camera
See also: Book of Optics and List of Chinese inventions
As far back as the 4th century BC, Greeks such as Aristotle and Euclid wrote on naturally-occurring rudimentary pinhole cameras. For example, light may travel through the slits of wicker baskets or the crossing of tree leaves. The ancient Greeks, however, believed that vision is enabled by rays emitted from the eye. The discovery that vision results from rays entering the eye rather than being emitted by it enabled a much better understanding of the pinhole camera effect. It was the 10th-century Arab physicist, astronomer and mathematician, Ibn al-Haytham (Alhazen), who published this idea in the Book of Optics in 1021 AD. He also invented the first pinhole camera after noticing the way light was streaming through a hole in a window shutter. He improved on the camera after realizing that the smaller the pinhole, the sharper the image (though the less light). He designed the first camera obscura (Lat. dark chamber). As a side benefit of his invention, he was credited with being first man to shift physics from a philosophical to an experimental basis
In the 5th century BC, the Mohist philosopher Mo Jing (墨經) in ancient China mentioned the effect of an inverted image forming through a pinhole. The image of an inverted Chinese pagoda is mentioned in Duan Chengshi's (d. 863) book Miscellaneous Morsels from Youyang written during the Tang Dynasty (618–907). Along with experimenting with the pinhole camera and the burning mirror of the ancient Mohists, the Song Dynasty (960–1279 AD) Chinese scientist Shen Kuo (1031-1095) experimented with camera obscura and was the first to establish geometrical and quantitative attributes for it.
In the 13th century, Robert Grosseteste and Roger Bacon commented on the pinhole camera.Between 1000 and 1600, men such as Ibn al-Haytham, Gemma Frisius, and Giambattista della Porta wrote on the pinhole camera, explaining why the images are upside down. Pinhole devices provide safety for the eyes when viewing solar eclipses because the event is observed indirectly, the diminished intensity of the pinhole image being harmless compared with the full glare of the sun itself.
Around 1600, Giambattista della Porta reinvented the pinhole camera. it was not until 1850 that a Scottish scientist by the name of Sir David Brewster actually took the first actual photography with a pinhole camera. Sir William Crookes and William de Wiveleslie Abney were other early photographers to try the pinhole technique.
Selection of pinhole size
Generally, a smaller pinhole (with a thinner surface that the hole goes through) will result in sharper image resolution as the projected circle of confusion is smaller at the image plane. The thinner and smaller the more resolution the less diffraction,this is why a lot of pinhole instructions tell you to sand the surface the hole is in. An extremely small hole, however, can produce significant diffraction effects and a less clear image due to the wave properties of light. Additionally, as the diameter of the hole approaches the thickness of the material in which it is punched, significant vignetting occurs, as less light reaches the edges of the image. This is due to the sides of the hole shading the light coming in at anything other than 90 degrees.
The best pinhole is perfectly round (since irregularities cause higher-order diffraction effects), and in an extremely thin piece of material. Industrially produced pinholes benefit from laser etching, but a hobbyist can still produce pinholes of sufficiently high quality for photographic work.
A photograph taken with a pinhole camera using an exposure time of 2 seconds
Some examples of photographs taken using a pinhole camera.One often quoted method is to start with a sheet of brass shim or metal reclaimed from an aluminium drinks can or tin foil/aluminum foil, use fine sand paper to reduce the thickness of the centre of the material to the minimum, before carefully creating a pinhole with a suitably sized needle - sanding away the burrs on either side & rotating the pin as it glides in and out in order to produce a smooth circular hole.
A method of calculating the optimal pinhole diameter was first attempted by Jozef Petzval. The formula used today was evolved by Lord Rayleigh:
where d is diameter, f is focal length (distance from hole to photographic film) and λ is the wavelength of light, all expressed in meters.
For standard black-and-white film, a wavelength of light corresponding to yellow-green (550 nm) should yield optimum results. (For a pinhole-to-film distance of 1 inch (25 mm), this works out to a pinhole .22 mm in diameter. For 5 cm, the appropriate diameter is .32 mm. )
The depth of field is basically infinite, but this does not mean that no optical blurring occurs. The infinite depth of field means that image blur depends not on object distance, but on other factors, such as the distance from the aperture to the film plane, the aperture size, and the wavelength(s) of the light source.
Pinhole camera construction
Pinhole cameras are usually handmade by the photographer for a particular purpose. In its simplest form, the photographic pinhole camera consists of a light-tight box with a pinhole in one end, and a piece of film or photographic paper wedged or taped into the other end. A flap of cardboard with a tape hinge can be used as a shutter. The pinhole is usually punched or drilled using a sewing needle or small diameter bit through a piece of tinfoil or thin aluminum or brass sheet. This piece is then taped to the inside of the light tight box behind a hole cut through the box. An oatmeal box can be made into an excellent pinhole camera.
Pinhole cameras are often constructed with a sliding film holder or back so that the distance between the film and the pinhole can be adjusted. This allows the angle of view of the camera to be changed and also the effective f-stop ratio of the camera. Moving the film closer to the pinhole will result in a wide angle field of view and a shorter exposure time. Moving the film farther away from the pinhole will result in a telephoto or narrow angle view and a longer exposure time.
Pinhole cameras can also be constructed by replacing the lens assembly in a conventional camera with a pinhole. In particular, compact 35 mm cameras whose lens and focusing assembly has been damaged can be reused as pinhole cameras—maintaining the use of the shutter and film winding mechanisms. As a result of the enormous increase in f-number while maintaining the same exposure time, one must use a fast film in direct sunshine.
See also: Book of Optics and List of Chinese inventions
As far back as the 4th century BC, Greeks such as Aristotle and Euclid wrote on naturally-occurring rudimentary pinhole cameras. For example, light may travel through the slits of wicker baskets or the crossing of tree leaves. The ancient Greeks, however, believed that vision is enabled by rays emitted from the eye. The discovery that vision results from rays entering the eye rather than being emitted by it enabled a much better understanding of the pinhole camera effect. It was the 10th-century Arab physicist, astronomer and mathematician, Ibn al-Haytham (Alhazen), who published this idea in the Book of Optics in 1021 AD. He also invented the first pinhole camera after noticing the way light was streaming through a hole in a window shutter. He improved on the camera after realizing that the smaller the pinhole, the sharper the image (though the less light). He designed the first camera obscura (Lat. dark chamber). As a side benefit of his invention, he was credited with being first man to shift physics from a philosophical to an experimental basis
In the 5th century BC, the Mohist philosopher Mo Jing (墨經) in ancient China mentioned the effect of an inverted image forming through a pinhole. The image of an inverted Chinese pagoda is mentioned in Duan Chengshi's (d. 863) book Miscellaneous Morsels from Youyang written during the Tang Dynasty (618–907). Along with experimenting with the pinhole camera and the burning mirror of the ancient Mohists, the Song Dynasty (960–1279 AD) Chinese scientist Shen Kuo (1031-1095) experimented with camera obscura and was the first to establish geometrical and quantitative attributes for it.
In the 13th century, Robert Grosseteste and Roger Bacon commented on the pinhole camera.Between 1000 and 1600, men such as Ibn al-Haytham, Gemma Frisius, and Giambattista della Porta wrote on the pinhole camera, explaining why the images are upside down. Pinhole devices provide safety for the eyes when viewing solar eclipses because the event is observed indirectly, the diminished intensity of the pinhole image being harmless compared with the full glare of the sun itself.
Around 1600, Giambattista della Porta reinvented the pinhole camera. it was not until 1850 that a Scottish scientist by the name of Sir David Brewster actually took the first actual photography with a pinhole camera. Sir William Crookes and William de Wiveleslie Abney were other early photographers to try the pinhole technique.
Selection of pinhole size
Generally, a smaller pinhole (with a thinner surface that the hole goes through) will result in sharper image resolution as the projected circle of confusion is smaller at the image plane. The thinner and smaller the more resolution the less diffraction,this is why a lot of pinhole instructions tell you to sand the surface the hole is in. An extremely small hole, however, can produce significant diffraction effects and a less clear image due to the wave properties of light. Additionally, as the diameter of the hole approaches the thickness of the material in which it is punched, significant vignetting occurs, as less light reaches the edges of the image. This is due to the sides of the hole shading the light coming in at anything other than 90 degrees.
The best pinhole is perfectly round (since irregularities cause higher-order diffraction effects), and in an extremely thin piece of material. Industrially produced pinholes benefit from laser etching, but a hobbyist can still produce pinholes of sufficiently high quality for photographic work.
A photograph taken with a pinhole camera using an exposure time of 2 seconds
Some examples of photographs taken using a pinhole camera.One often quoted method is to start with a sheet of brass shim or metal reclaimed from an aluminium drinks can or tin foil/aluminum foil, use fine sand paper to reduce the thickness of the centre of the material to the minimum, before carefully creating a pinhole with a suitably sized needle - sanding away the burrs on either side & rotating the pin as it glides in and out in order to produce a smooth circular hole.
A method of calculating the optimal pinhole diameter was first attempted by Jozef Petzval. The formula used today was evolved by Lord Rayleigh:
where d is diameter, f is focal length (distance from hole to photographic film) and λ is the wavelength of light, all expressed in meters.
For standard black-and-white film, a wavelength of light corresponding to yellow-green (550 nm) should yield optimum results. (For a pinhole-to-film distance of 1 inch (25 mm), this works out to a pinhole .22 mm in diameter. For 5 cm, the appropriate diameter is .32 mm. )
The depth of field is basically infinite, but this does not mean that no optical blurring occurs. The infinite depth of field means that image blur depends not on object distance, but on other factors, such as the distance from the aperture to the film plane, the aperture size, and the wavelength(s) of the light source.
Pinhole camera construction
Pinhole cameras are usually handmade by the photographer for a particular purpose. In its simplest form, the photographic pinhole camera consists of a light-tight box with a pinhole in one end, and a piece of film or photographic paper wedged or taped into the other end. A flap of cardboard with a tape hinge can be used as a shutter. The pinhole is usually punched or drilled using a sewing needle or small diameter bit through a piece of tinfoil or thin aluminum or brass sheet. This piece is then taped to the inside of the light tight box behind a hole cut through the box. An oatmeal box can be made into an excellent pinhole camera.
Pinhole cameras are often constructed with a sliding film holder or back so that the distance between the film and the pinhole can be adjusted. This allows the angle of view of the camera to be changed and also the effective f-stop ratio of the camera. Moving the film closer to the pinhole will result in a wide angle field of view and a shorter exposure time. Moving the film farther away from the pinhole will result in a telephoto or narrow angle view and a longer exposure time.
Pinhole cameras can also be constructed by replacing the lens assembly in a conventional camera with a pinhole. In particular, compact 35 mm cameras whose lens and focusing assembly has been damaged can be reused as pinhole cameras—maintaining the use of the shutter and film winding mechanisms. As a result of the enormous increase in f-number while maintaining the same exposure time, one must use a fast film in direct sunshine.
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