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70-568: The D700's full-frame sensor allows the use of F-mount (FX) lenses to their fullest advantage, with almost no crop factor . When a cropped DX lens is mounted on the D700, either the DX-sized portion, or the (vignetted) FX-sized portion of the camera's sensor can be used. The D700 has a built in autofocus motor for all Nikon autofocus- lenses , includes CPU and metering for older Nikon F-mount AI/AI-S lenses, and supports PC-E lenses . The D700 bears

140-525: A CPU enabled lens; the aperture of G designated lenses cannot be controlled without an electronic camera body; non-AI lenses (manufactured prior to 1977) can cause mechanical damage to later model bodies unless they are modified to meet the AI specification; and AF-P lenses (introduced in 2016) will not focus, even manually, on cameras introduced before roughly 2013. Many manual focus lenses can be converted to allow metering with consumer Nikon bodies by adding

210-570: A Dandelion chip to the lens. Most Nikon F-mount lenses cover a minimum of the standard 36×24   mm area of 35mm format and the Nikon FX format , while DX designated lenses cover the 24×16   mm area of the Nikon DX format , and industrial F-mount lenses have varying coverage. DX lenses may produce vignetting when used on film and FX cameras. However, Nikon lenses designed for film cameras will work on Nikon digital system cameras with

280-468: A NASA/Zeiss 50mm f/0.7 , the fastest lens in film history. Beyond the expense, these lenses have limited application due to the correspondingly shallower depth of field (DOF)  – the scene must either be shallow, shot from a distance, or will be significantly defocused, though this may be the desired effect. Zoom lenses typically have a maximum relative aperture (minimum f-number) of f /2.8 to f /6.3 through their range. High-end lenses will have

350-410: A 100-centimetre (39 in) aperture. The aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system. In astrophotography , the aperture may be given as a linear measure (for example, in inches or millimetres) or as the dimensionless ratio between that measure and

420-406: A PC-E lens operates like a PC lens. The PC Micro-Nikkor 85   mm f / 2.8D lens offers only preset aperture control, actuated mechanically by pressing a plunger. In July 1962, Nikon released the first interchangeable perspective-control lens available for a single-lens reflex camera , the 35mm f / 3.5 PC-Nikkor. This was followed in 1968 by a redesigned 35mm f / 2.8 PC-Nikkor in which

490-448: A brightly lit place to 8 mm ( f /2.1 ) in the dark as part of adaptation . In rare cases in some individuals are able to dilate their pupils even beyond 8 mm (in scotopic lighting, close to the physical limit of the iris. In humans, the average iris diameter is about 11.5 mm, which naturally influences the maximal size of the pupil as well, where larger iris diameters would typically have pupils which are able to dilate to

560-554: A certain point, there is no further sharpness benefit to stopping down, and the diffraction occurred at the edges of the aperture begins to become significant for imaging quality. There is accordingly a sweet spot, generally in the f /4 – f /8 range, depending on lens, where sharpness is optimal, though some lenses are designed to perform optimally when wide open. How significant this varies between lenses, and opinions differ on how much practical impact this has. While optimal aperture can be determined mechanically, how much sharpness

630-423: A constant aperture, such as f /2.8 or f /4 , which means that the relative aperture will stay the same throughout the zoom range. A more typical consumer zoom will have a variable maximum relative aperture since it is harder and more expensive to keep the maximum relative aperture proportional to the focal length at long focal lengths; f /3.5 to f /5.6 is an example of a common variable aperture range in

700-594: A consumer zoom lens. By contrast, the minimum aperture does not depend on the focal length – it is limited by how narrowly the aperture closes, not the lens design – and is instead generally chosen based on practicality: very small apertures have lower sharpness due to diffraction at aperture edges, while the added depth of field is not generally useful, and thus there is generally little benefit in using such apertures. Accordingly, DSLR lens typically have minimum aperture of f /16 , f /22 , or f /32 , while large format may go down to f /64 , as reflected in

770-498: A feature extended to their E-type range in 2013. Optimal aperture depends both on optics (the depth of the scene versus diffraction), and on the performance of the lens. Optically, as a lens is stopped down, the defocus blur at the Depth of Field (DOF) limits decreases but diffraction blur increases. The presence of these two opposing factors implies a point at which the combined blur spot is minimized ( Gibson 1975 , 64); at that point,

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840-404: A few long telephotos , lenses mounted on bellows , and perspective-control and tilt/shift lenses, the mechanical linkage was impractical, and automatic aperture control was not provided. Many such lenses incorporated a feature known as a "preset" aperture, which allows the lens to be set to working aperture and then quickly switched between working aperture and full aperture without looking at

910-443: A greater aperture which allows more light to reach the film or image sensor. The photography term "one f-stop" refers to a factor of √ 2 (approx. 1.41) change in f-number which corresponds to a √ 2 change in aperture diameter, which in turn corresponds to a factor of 2 change in light intensity (by a factor 2 change in the aperture area). Aperture priority is a semi-automatic shooting mode used in cameras. It permits

980-456: A lens used for large format photography. Thus the optical elements built into the lens can be far smaller and cheaper. In exceptional circumstances lenses can have even wider apertures with f-numbers smaller than 1.0; see lens speed: fast lenses for a detailed list. For instance, both the current Leica Noctilux-M 50mm ASPH and a 1960s-era Canon 50mm rangefinder lens have a maximum aperture of f /0.95 . Cheaper alternatives began appearing in

1050-509: A mechanical pushbutton that sets working aperture when pressed and restores full aperture when pressed a second time. Canon EF lenses, introduced in 1987, have electromagnetic diaphragms, eliminating the need for a mechanical linkage between the camera and the lens, and allowing automatic aperture control with the Canon TS-E tilt/shift lenses. Nikon PC-E perspective-control lenses, introduced in 2008, also have electromagnetic diaphragms,

1120-535: A new optical design. This was the last of the completely manual PC-Nikkors to be offered. Nikkor lenses designated AF-S, AF-I and AF-P have integrated autofocus motors, but other manufacturers included in the list do not designate it as clearly. These lenses are needed for autofocus on certain newer low-end Nikon cameras which lack an autofocus motor . Without autofocus motor are the Nikon D40 , D40X , D60 , D3xxx (most recent: D3500 ), D5xxx (most recent: D5600 ),

1190-417: A part in the depth of field in an image. An aperture's f-number is not modified by the camera's sensor size because it is a ratio that only pertains to the attributes of the lens. Instead, the higher crop factor that comes as a result of a smaller sensor size means that, in order to get an equal framing of the subject, the photo must be taken from further away, which results in a less blurry background, changing

1260-601: A physical similarity to the Nikon D300 , which uses the same MB-D10 battery pack and EN-EL3e battery. It was discontinued on August 24, 2012. The Nikon D700 has been tested by many independent reviewers and has generally received high marks. It achieved a top ranking in the DxOmark Sensor ranking and was, as of November 2011, ranked ninth behind the Nikon D3 , Nikon D3S , Nikon D3X , four medium format cameras and

1330-834: A regular rate, solely for and about the D700. Further affirming its continued relevance, many professionals still consider it their main camera for project or personal work, and a backup for professional engagements. The D700 is considered by many as an icon. Nikon Z cameras >> PROCESSOR : Pre-EXPEED | EXPEED | EXPEED 2 | EXPEED 3 | EXPEED 4 | EXPEED 5 | EXPEED 6 VIDEO: HD video / Video AF / Uncompressed / 4k video   ⋅   SCREEN: Articulating , Touchscreen   ⋅   BODY FEATURE: Weather Sealed Without full AF-P lens support   ⋅   Without AF-P and without E-type lens support   ⋅   Without an AF motor (needs lenses with integrated motor , except D50 ) Nikon F-mount The Nikon F-mount

1400-434: A result, it also determines the ray cone angle and brightness at the image point (see exit pupil ). The aperture stop generally depends on the object point location; on-axis object points at different object planes may have different aperture stops, and even object points at different lateral locations at the same object plane may have different aperture stops ( vignetted ). In practice, many object systems are designed to have

1470-424: A single aperture stop at designed working distance and field of view . In some contexts, especially in photography and astronomy , aperture refers to the opening diameter of the aperture stop through which light can pass. For example, in a telescope , the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example,

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1540-439: A slower lens) f /2.8 – f /5.6 , f /5.6 – f /11 , and f /11 – f /22 . These are not sharp divisions, and ranges for specific lenses vary. The specifications for a given lens typically include the maximum and minimum aperture (opening) sizes, for example, f /0.95 – f /22 . In this case, f /0.95 is currently the maximum aperture (the widest opening on a full-frame format for practical use ), and f /22

1610-400: A very large final image viewed at normal distance, or a portion of an image enlarged to normal size ( Hansma 1996 ). Hansma also suggests that the final-image size may not be known when a photograph is taken, and obtaining the maximum practicable sharpness allows the decision to make a large final image to be made at a later time; see also critical sharpness . In many living optical systems ,

1680-405: A wider extreme than those with smaller irises. Maximum dilated pupil size also decreases with age. The iris controls the size of the pupil via two complementary sets muscles, the sphincter and dilator muscles, which are innervated by the parasympathetic and sympathetic nervous systems respectively, and act to induce pupillary constriction and dilation respectively. The state of the pupil

1750-422: Is required depends on how the image will be used – if the final image is viewed under normal conditions (e.g., an 8″×10″ image viewed at 10″), it may suffice to determine the f -number using criteria for minimum required sharpness, and there may be no practical benefit from further reducing the size of the blur spot. But this may not be true if the final image is viewed under more demanding conditions, e.g.,

1820-529: Is a type of interchangeable lens mount developed by Nikon for its 35mm format single-lens reflex cameras . The F-mount was first introduced on the Nikon F camera in 1959, and features a three-lug bayonet mount with a 44   mm throat and a flange to focal plane distance of 46.5   mm. The company continues, with the 2020 D6 model, to use variations of the same lens mount specification for its film and digital SLR cameras . The Nikon F-mount successor

1890-429: Is also used in other contexts to indicate a system which blocks off light outside a certain region. In astronomy, for example, a photometric aperture around a star usually corresponds to a circular window around the image of a star within which the light intensity is assumed. The aperture stop is an important element in most optical designs. Its most obvious feature is that it limits the amount of light that can reach

1960-519: Is closely influenced by various factors, primarily light (or absence of light), but also by emotional state, interest in the subject of attention, arousal , sexual stimulation , physical activity, accommodation state, and cognitive load . The field of view is not affected by the size of the pupil. Some individuals are also able to directly exert manual and conscious control over their iris muscles and hence are able to voluntarily constrict and dilate their pupils on command. However, this ability

2030-523: Is opposite of the direction normally used by Canon . F-mount lenses also typically have aperture rings that turn clockwise to close. The aperture rings have two sets of f-stop numbers. On cameras equipped with Nikon's Aperture Direct Readout (ADR) system, a small window under the pentaprism reads the smaller scale and displays the selected f-stop in the viewfinder . Nikon has introduced many proprietary designations for F-mount Nikkor lenses, reflecting design variations and developments both in lenses and

2100-457: Is rare and potential use or advantages are unclear. In digital photography, the 35mm-equivalent aperture range is sometimes considered to be more important than the actual f-number. Equivalent aperture is the f-number adjusted to correspond to the f-number of the same size absolute aperture diameter on a lens with a 35mm equivalent focal length . Smaller equivalent f-numbers are expected to lead to higher image quality based on more total light from

2170-637: Is the Nikon Z-mount . The Nikon F-mount is one of only two SLR lens mounts (the other being the Pentax K-mount ) which were not abandoned by their associated manufacturer upon the introduction of autofocus , but rather extended to meet new requirements related to metering , autofocus , and aperture control. The large variety of F-mount compatible lenses makes it the largest system of interchangeable flange-mount photographic lenses in history. Over 400 different Nikkor lenses are compatible with

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2240-431: Is the minimum aperture (the smallest opening). The maximum aperture tends to be of most interest and is always included when describing a lens. This value is also known as the lens "speed" , as it affects the exposure time. As the aperture area is proportional to the light admitted by a lens or an optical system, the aperture diameter is proportional to the square root of the light admitted, and thus inversely proportional to

2310-471: The f -number is optimal for image sharpness, for this given depth of field  – a wider aperture (lower f -number) causes more defocus, while a narrower aperture (higher f -number) causes more diffraction. As a matter of performance, lenses often do not perform optimally when fully opened, and thus generally have better sharpness when stopped down some – this is sharpness in the plane of critical focus , setting aside issues of depth of field. Beyond

2380-468: The Graflex large format reflex camera an automatic aperture control, not all early 35mm single lens reflex cameras had the feature. With a small aperture, this darkened the viewfinder, making viewing, focusing, and composition difficult. Korling's design enabled full-aperture viewing for accurate focus, closing to the pre-selected aperture opening when the shutter was fired and simultaneously synchronising

2450-497: The Nikon 1 series with FT1 adapter and the Nikon Z-mount cameras with FTZ adapter. Zeiss ZF series lenses are manual-focus designs Nikon AI-S type aperture indexing. They are manufactured by Cosina to Zeiss specifications. Four design variations are designated ZF, ZF.2, ZF-I, and ZF-IR. ZF is the original product line. ZF.2 lenses are CPU-enabled (similar to Nikon AI-P lenses) offering full metering compatibility with

2520-503: The Pentax Spotmatic ) required that the lens be stopped down to the working aperture when taking a meter reading. Subsequent models soon incorporated mechanical coupling between the lens and the camera body, indicating the working aperture to the camera for exposure while allowing the lens to be at its maximum aperture for composition and focusing; this feature became known as open-aperture metering . For some lenses, including

2590-544: The aperture of an optical system (including a system consisted of a single lens) is a hole or an opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image of the aperture and focal length of an optical system determine the cone angle of a bundle of rays that comes to a focus in the image plane . An optical system typically has many openings or structures that limit ray bundles (ray bundles are also known as pencils of light). These structures may be

2660-399: The focal length . In other photography, it is usually given as a ratio. A usual expectation is that the term aperture refers to the opening of the aperture stop, but in reality, the term aperture and the aperture stop are mixed in use. Sometimes even stops that are not the aperture stop of an optical system are also called apertures. Contexts need to clarify these terms. The word aperture

2730-455: The iris of the eye  – it controls the effective diameter of the lens opening (called pupil in the eyes). Reducing the aperture size (increasing the f-number) provides less light to sensor and also increases the depth of field (by limiting the angle of cone of image light reaching the sensor), 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,

2800-941: The 36×24 mm area of the 35mm format or Nikon FX format , and lenses 28 mm and longer share a common T-stop (T/) of 2.1. Nikkorex F / Nikkor J Autofocus Camera | APS-format | Nikkorex with Leaf Shutter | Nikomat/Nikkormat | All Other Cameras | Manual Focus with electronic features (A mode) See also: Nikon DSLR cameras Nikon Z cameras >> PROCESSOR : Pre-EXPEED | EXPEED | EXPEED 2 | EXPEED 3 | EXPEED 4 | EXPEED 5 | EXPEED 6 VIDEO: HD video / Video AF / Uncompressed / 4k video   ⋅   SCREEN: Articulating , Touchscreen   ⋅   BODY FEATURE: Weather Sealed Without full AF-P lens support   ⋅   Without AF-P and without E-type lens support   ⋅   Without an AF motor (needs lenses with integrated motor , except D50 ) Aperture In optics ,

2870-631: The APS-C sized Pentax K-5 . The camera received several awards, including a Digital Photography Review "Highly Recommended" award. In the years following its release, the D700 has retained its status as a capable camera, and has established itself a legend in the world of digital photography. As of 2024, many prominent photography outlets continue to praise the D700. In recent years, and unlike any other DSLR , further and updated reviews have been published, YouTube videos uploaded, with web forums, entire websites, and social media pages dedicated and updated at

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2940-643: The F-mount in non-photographic imaging applications. The F-mount has a significant degree of both backward and forward compatibility . Many current autofocus F-mount lenses can be used on the original Nikon F , and the earliest manual-focus F-mount lenses of the 1960s and early 1970s can, with some modification, still be used to their fullest on all professional-class Nikon cameras. Incompatibilities do exist, however, and adventurous F-mount users should consult product documentation in order to avoid problems. For example, many electronic camera bodies cannot meter without

3010-484: The F-mount itself. There are also "unofficial" designations used by collectors and dealers to differentiate similar lenses. Nikon PC lenses, like other perspective control lenses , offer adjustments that duplicate certain view camera movements . The 28mm and 35mm PC lenses support shifting the lens in relation to the film or sensor plane, while Nikon's 19mm, 24mm, 45mm, and 85mm PC-E lenses also support tilting . Nikon currently offers four different PC lenses for sale:

3080-424: The aperture control. A typical operation might be to establish rough composition, set the working aperture for metering, return to full aperture for a final check of focus and composition, and focusing, and finally, return to working aperture just before exposure. Although slightly easier than stopped-down metering, operation is less convenient than automatic operation. Preset aperture controls have taken several forms;

3150-429: The aperture size will regulate the film's or image sensor's degree of exposure to light. Typically, a fast shutter will require a larger aperture to ensure sufficient light exposure, and a slow shutter will require a smaller aperture to avoid excessive exposure. A device called a diaphragm usually serves as the aperture stop and controls the aperture (the opening of the aperture stop). The diaphragm functions much like

3220-445: The area of the entrance pupil that is the object space-side image of the aperture of the system, equal to: Where the two equivalent forms are related via the f-number N = f / D , with focal length f and entrance pupil diameter D . The focal length value is not required when comparing two lenses of the same focal length; a value of 1 can be used instead, and the other factors can be dropped as well, leaving area proportion to

3290-422: The changed depth of field, nor the perceived change in light sensitivity are a result of the aperture. Instead, equivalent aperture can be seen as a rule of thumb to judge how changes in sensor size might affect an image, even if qualities like pixel density and distance from the subject are the actual causes of changes in the image. The terms scanning aperture and sampling aperture are often used to refer to

3360-407: The common 35 mm film format in general production have apertures of f /1.2 or f /1.4 , with more at f /1.8 and f /2.0 , and many at f /2.8 or slower; f /1.0 is unusual, though sees some use. When comparing "fast" lenses, the image format used must be considered. Lenses designed for a small format such as half frame or APS-C need to project a much smaller image circle than

3430-647: The early 2010s, such as the Cosina Voigtländer f /0.95 Nokton (several in the 10.5–60 mm range) and f /0.8 ( 29 mm ) Super Nokton manual focus lenses in the for the Micro Four-Thirds System , and the Venus Optics (Laowa) Argus 35 mm f /0.95 . Professional lenses for some movie cameras have f-numbers as small as f /0.75 . Stanley Kubrick 's film Barry Lyndon has scenes shot by candlelight with

3500-404: The edge of a lens or mirror , or a ring or other fixture that holds an optical element in place or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that primarily determines the cone of rays that an optical system accepts (see entrance pupil ). As

3570-504: The eye consists of an iris which adjusts the size of the pupil , through which light enters. The iris is analogous to the diaphragm, and the pupil (which is the adjustable opening in the iris) the aperture. Refraction in the cornea causes the effective aperture (the entrance pupil in optics parlance) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it can range from as narrow as 2 mm ( f /8.3 ) in diameter in

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3640-609: The firing of a flash unit. From 1956 SLR camera manufacturers separately developed automatic aperture control (the Miranda T 'Pressure Automatic Diaphragm', and other solutions on the Exakta Varex IIa and Praktica FX2 ) allowing viewing at the lens's maximum aperture, stopping the lens down to the working aperture at the moment of exposure, and returning the lens to maximum aperture afterward. The first SLR cameras with internal ( "through-the-lens" or "TTL" ) meters (e.g.,

3710-457: The four PC-E Nikkors (2008 and 2016), and the 85mm PC-Nikkor (1999). The 45   mm and 85   mm "Micro" lenses offer close focus (0.5 magnification) for macrophotography . The PC- E lenses (the "E" designates an electromagnetic diaphragm) offer automatic aperture control with all DSLRs with CMOS image sensor except the Nikon D90 . With earlier DSLRs and all "analog" film camera models,

3780-449: The full range of AF Nikon SLR cameras. ZF-I lenses add mechanical locks for focus and aperture, and additional environmental sealing, for industrial applications. ZF-IR lenses are adapted to infrared imaging, with coatings that transmit wavelengths up to 1100 nm, and focus scales marked for infrared. CP.2 lenses are a series of Zeiss "CompactPrime" cinema lenses which present F-mount as one of three mounting options. The lenses cover

3850-457: The image/ film plane . This can be either unavoidable due to the practical limit of the aperture stop size, or deliberate to prevent saturation of a detector or overexposure of film. In both cases, the size of the aperture stop determines the amount of light admitted by an optical system. The aperture stop also affects other optical system properties: In addition to an aperture stop, a photographic lens may have one or more field stops , which limit

3920-403: The limitations noted above. F-mount lenses lock by turning counter-clockwise (when looking at the front of lens) and unlock clockwise. Nearly all F-mount lenses have zoom and focus controls that rotate in the clockwise direction (as viewed from behind the camera) to increase focal length and focus distance respectively. This convention is also used in Pentax K-mount and Sony A-mount lenses but

3990-495: The maximum amount of light from the distant objects being imaged. The size of the aperture is limited, however, in practice by considerations of its manufacturing cost and time and its weight, as well as prevention of aberrations (as mentioned above). Apertures are also used in laser energy control, close aperture z-scan technique , diffractions/patterns, and beam cleaning. Laser applications include spatial filters , Q-switching , high intensity x-ray control. In light microscopy,

4060-539: The most common has been the use of essentially two lens aperture rings, with one ring setting the aperture and the other serving as a limit stop when switching to working aperture. Examples of lenses with this type of preset aperture control are the Nikon PC Nikkor 28 mm f /3.5 and the SMC Pentax Shift 6×7 75 mm f /4.5 . The Nikon PC Micro-Nikkor 85 mm f /2.8D lens incorporates

4130-462: The name of Group f/64 . Depth of field is a significant concern in macro photography , however, and there one sees smaller apertures. For example, the Canon MP-E 65mm can have effective aperture (due to magnification) as small as f /96 . The pinhole optic for Lensbaby creative lenses has an aperture of just f /177 . The amount of light captured by an optical system is proportional to

4200-427: The opening through which an image is sampled, or scanned, for example in a Drum scanner , an image sensor , or a television pickup apparatus. The sampling aperture can be a literal optical aperture, that is, a small opening in space, or it can be a time-domain aperture for sampling a signal waveform. For example, film grain is quantified as graininess via a measurement of film density fluctuations as seen through

4270-421: The perceived depth of field. Similarly, a smaller sensor size with an equivalent aperture will result in a darker image because of the pixel density of smaller sensors with equivalent megapixels. Every photosite on a camera's sensor requires a certain amount of surface area that is not sensitive to light, a factor that results in differences in pixel pitch and changes in the signal-noise ratio . However, neither

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4340-577: The photographer to select an aperture setting and let the camera decide the shutter speed and sometimes also ISO sensitivity for the correct exposure. This is also referred to as Aperture Priority Auto Exposure, A mode, AV mode (aperture-value mode), or semi-auto mode. Typical ranges of apertures used in photography are about f /2.8 – f /22 or f /2 – f /16 , covering six stops, which may be divided into wide, middle, and narrow of two stops each, roughly (using round numbers) f /2 – f /4 , f /4 – f /8 , and f /8 – f /16 or (for

4410-540: The reciprocal square of the f-number N . If two cameras of different format sizes and focal lengths have the same angle of view , and the same aperture area, they gather the same amount of light from the scene. In that case, the relative focal-plane illuminance , however, would depend only on the f-number N , so it is less in the camera with the larger format, longer focal length, and higher f-number. This assumes both lenses have identical transmissivity. Though as early as 1933 Torkel Korling had invented and patented for

4480-477: The shifting portion of the lens was further from the camera's body, in order to clear the new "Photomic" meters. The last optical redesign of this 35mm lens was released in 1980. The 35mm PC-Nikkor did not meet the need of photographers for a wider-angle lens, so in July 1975 Nikon released the 28mm f / 4 PC-Nikkor. In February 1981 Nikon released an improved version of this lens, the 28mm f / 3.5 PC-Nikkor, with

4550-421: The smaller the aperture (the larger the f-number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus. The lens aperture is usually specified as an f-number , the ratio of focal length to effective aperture diameter (the diameter of the entrance pupil ). A lens typically has a set of marked "f-stops" that the f-number can be set to. A lower f-number denotes

4620-457: The square root of required exposure time, such that an aperture of f /2 allows for exposure times one quarter that of f /4 . ( f /2 is 4 times larger than f /4 in the aperture area.) Lenses with apertures opening f /2.8 or wider are referred to as "fast" lenses, although the specific point has changed over time (for example, in the early 20th century aperture openings wider than f /6 were considered fast. The fastest lenses for

4690-419: The subject, as well as lead to reduced depth of field. For example, a Sony Cyber-shot DSC-RX10 uses a 1" sensor, 24 – 200 mm with maximum aperture constant along the zoom range; f /2.8 has equivalent aperture range f /7.6 , which is a lower equivalent f-number than some other f /2.8 cameras with smaller sensors. However, modern optical research concludes that sensor size does not actually play

4760-447: The system's field of view . When the field of view is limited by a field stop in the lens (rather than at the film or sensor) vignetting results; this is only a problem if the resulting field of view is less than was desired. In astronomy, the opening diameter of the aperture stop (called the aperture ) is a critical parameter in the design of a telescope . Generally, one would want the aperture to be as large as possible, to collect

4830-600: The system. The F-mount is also popular in scientific and industrial applications, most notably machine vision . The F-mount has been in production for over 60 years, the only SLR lens mount with such longevity. In addition to Nikon's own range of " Nikkor " lenses, brands of F-mount photographic lenses include Zeiss , Voigtländer , Schneider , Angénieux , Samyang , Sigma , Tokina , Tamron , Hartblei , Kiev-Arsenal , Lensbaby , and Vivitar . F-mount cameras include current models from Nikon , Fujifilm , Sinar , JVC , Kenko and Horseman. Numerous other manufacturers employ

4900-455: The word aperture may be used with reference to either the condenser (that changes the angle of light onto the specimen field), field iris (that changes the area of illumination on specimens) or possibly objective lens (forms primary images). See Optical microscope . The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or image sensor . In combination with variation of shutter speed ,

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