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In optics, an aperture is something which restricts the diameter of the light path through one plane in an optical system. This may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or it may be a special element placed in the optical path deliberately to limit the light admitted by the system. The aperture stop or simply the stop is the limiting aperture of the system—the aperture which restricts the diameter of the cone or cylinder of light that can enter and pass through the system. The diameter of the aperture stop is sometimes simply referred to as the aperture of the system, especially when speaking of cameras and telescopes. Note that the aperture stop is not necessarily the smallest aperture in the system. Magnification and demagnification by lenses and other elements can cause a relatively large aperture to be the stop for the system. Related topic: List of optical topics Optics (appearance or look in ancient Greek) is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. ...
A lens. ...
A mirror is a surface with good specular reflection that is smooth enough to form an image. ...
For the geometric term, see diameter. ...
A camera is a device used to take pictures (usually photographs), either singly or in sequence, with or without sound recording, such as with video cameras. ...
50 cm refracting telescope at Nice Observatory. ...
Application
The aperture stop is an extremely important element in most optical designs. Its most obvious function is to reduce the amount of light that can reach the image plane, to prevent saturation of a detector or overexposure of film. The aperture stop has far more important functions, however: For images in Wikipedia, see Wikipedia:Images. ...
- The size of the stop determines the depth of field of the system. Smaller stops produce a longer depth of field, allowing objects at a wide range of distances to all be in focus at the same time.
- The stop limits the effect of optical aberrations. If the stop is too large, the image will be distorted. More sophisticated optical system designs can mitigate the effect of aberrations, allowing a larger stop and therefore greater light collecting ability.
- The stop determines the system's field of view.
- The stop determines whether the image will be vignetted. Larger stops cause the intensity reaching the film or detector to fall off toward the edges of the picture.
The pupil of the eye is its aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it can range from 2 mm (f/8.3) in a brightly lit place to 8 mm (f/2.1) in the dark. An example of very shallow depth of field in a macro photograph. ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
In photography vignetting refer to a reduction in image brightness in the image periphery compared to the image center. ...
The human eye The pupil is the central transparent area (showing as black). ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber and provides most of an eyes optical power [1]. Together with the lens, the cornea refracts light and consequently helps the eye to focus. ...
In photography The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or digital sensor (CCD or CMOS). In combination with variation of shutter speed and film speed, the aperture size will regulate the film's degree of exposure to light. Typically, a fast shutter speed will require a larger aperture to ensure sufficient light exposure, and a slow shutter speed will require a smaller aperture to avoid excessive exposure. Photographic lens The zoom lens of the Canon Elph A photographic lens (or more correctly, objective) is an optical lens used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically. ...
Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific setting, electromagnetic radiation of any wavelength. ...
Undeveloped Arista black and white film, ISO 125. ...
A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...
Static CMOS Inverter CMOS (pronounced see-moss), which stands for complementary metal-oxide-semiconductor, is a major class of integrated circuits. ...
The shutter speed dial of a Fujica STX-1. ...
Film speed is the measure of a photographic film stocks sensitivity to light. ...
A photograph with an exposure time of 25 seconds In photography, exposure is the total amount of light allowed to fall on the sensor (photographic film or CCD) during the process of taking a photograph. ...
A device called a diaphragm controls the aperture. The diaphragm can be considered to function much like the pupil of the eye—it controls the effective diameter of the lens opening. Reducing the aperture size increases the depth of field, which describes the extent to which subject matter lying closer than or farther from the actual plane of focus appears to be in focus. In general, the smaller the aperture (the larger the number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus. This article is a translation from the Dutch article on diafragma Categories: Stub ...
The human eye The pupil is the central transparent area (showing as black). ...
This article needs to be cleaned up to conform to a higher standard of quality. ...
For the geometric term, see diameter. ...
An example of very shallow depth of field in a macro photograph. ...
 Diagram of decreasing aperture f-stops Aperture is usually measured in f-numbers. A lens will have a set of "f-stops" that represent doublings in the amount of light let through the aperture. A lower f-stop number denotes a greater aperture opening which allows more light to reach the film. A typical standard lens will have an f-stop range from f/16 (small aperture) to f/2 (large aperture). Professional lenses can have f-stops as low as f/1.0 (very large aperture). These are known as "fast" lenses because they allow much more light to reach the film and therefore reduce the required exposure time. Large aperture prime lenses (lenses which have a fixed focal length) are favored especially by photojournalists who often work in dim light, have no opportunity to introduce supplementary lighting, and capture fast breaking events. Description: Diagram of decreasing aperture sizes. ...
Description: Diagram of decreasing aperture sizes. ...
A 35mm lens set to f/11, as indicated by the white dot above the f-stop scale on the aperture ring In photography the f-number (focal ratio) expresses the diameter of the diaphragm aperture in terms of the effective focal length of the lens. ...
Categories: Stub | Lenses by type | Optics ...
Zoom lenses typically go from f/2.8 to f/6.3. A very fast zoom lens will be constant f/2.8, which means the aperture will stay the same throughout the zoom range. A normal zoom will be a constant f/4, and a consumer zoom will typically have a variable diaphragm, normally being something along the lines of f/4.5 to f/5.6, or even f/4.5 to f/6.3 (rare). There are a few exceptions to this rule, as even high quality hyperzooms often have as slow of an aperture as f/5.6 throughout the whole zoom range. Such is the case with most lenses which have more than 4x zoom range, like a 100-400 mm f/5.6. A Canon Inc. ...
A Canon 28-300mm modern professional zoom. ...
The reason for consumer zooms to have a variable aperture is that the f-number is proportional to the ratio of the focal length to the diameter of the diaphragm opening. This means that if you have a 75-300 mm lens, a physically bigger diaphragm opening will be needed at 300 mm than at 75 mm, to maintain the same f-number. More light is needed as the focal length increases, to compensate for the fact that light from a smaller field of view is being spread over the same area of film or detector. The focal point F and focal length f of a positive lens, a negative lens, a concave mirror, and a convex mirror. ...
Maximum and minimum apertures
 f/32 - narrow aperture and low shutter speed |
 f/5 - wide aperture and high shutter speed | The specifications for a given lens might include the minimum and maximum apertures. These refer to the maximum and minimum f-numbers the lens can be set at to achieve, respectively, the minimum and maximum input of light. For example, the Canon EF 70-200mm lens has a maximum aperture of f/2.8 and a minimum aperture of f/32. This may seem counterintuitive since the maximum aperture has a smaller number while the minimum aperture has a larger number, but makes sense since the smaller number corresponds to a physically larger aperture opening. This can be remembered by thinking of the f/numbers as fractions and recalling that 1/2.8 is greater than 1/32. Image File history File links Download high resolution version (1600x1054, 189 KB) File links The following pages link to this file: Depth of field Aperture Bokeh ...
Image File history File links Download high resolution version (1600x1054, 189 KB) File links The following pages link to this file: Depth of field Aperture Bokeh ...
Image File history File links Download high resolution version (1600x1054, 80 KB) Jonquil flowers shot at a fairly high aperture, f/5 File links The following pages link to this file: Depth of field Aperture Bokeh ...
Image File history File links Download high resolution version (1600x1054, 80 KB) Jonquil flowers shot at a fairly high aperture, f/5 File links The following pages link to this file: Depth of field Aperture Bokeh ...
The F2. ...
It should be noted that the maximum aperture tends to be of most interest (makes it easier to shoot under dim lighing conditions because the lens lets more light through to the film or CCD) and is usually included when describing a lens (e.g., 100-400mm f/5.6, 70-200mm f/2.8).
The minimum aperture is useful for time-lapse pictures shot on film (it places an upper limit on the exposure time for a given lighting condition) and maximum depth of field.
See also An example of very shallow depth of field in a macro photograph. ...
A scene from Jean Renoirs film, The Rules of the Game (1939). ...
A scene from William Wylers film, The Best Years of Our Lives, exemplifies deep focus. ...
This article is a translation from the Dutch article on diafragma Categories: Stub ...
The exit pupil is a concept in optics, and is defined as the minimum diameter of the light beam leaving an eyepiece though which all of the light from the eyepiece passes. ...
The human eye The pupil is the central transparent area (showing as black). ...
References Supporters contend that the Eleventh Edition of the Encyclopædia Britannica (1910-1911) represents the sum of human knowledge at the beginning of the 20th century; indeed, it was advertised as such. ...
The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...
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