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90-413: The camera bodies are complex; for example, the first model includes nearly 1100 parts, with seven principal alloy pressure castings and additional stamped cover plates to complete the structure. However, it is rugged and roller bearings are used in the aperture mechanism. Inevitably it requires a specialist for its repair; 43 parts have to be dismantled to remove the top plate for internal access. There

180-488: A surface , denoted H e ("e" for "energetic", to avoid confusion with photometric quantities) and measured in J/m , is given by where Luminous exposure of a surface , denoted H v ("v" for "visual", to avoid confusion with radiometric quantities) and measured in lx⋅s , is given by where If the measurement is adjusted to account only for light that reacts with the photo-sensitive surface, that is, weighted by

270-467: A tire flattens where it contacts the road. The race also yields slightly where each ball presses against it. Thus, the contact between ball and race is of finite size and has finite pressure. The deformed ball and race do not roll entirely smoothly because different parts of the ball are moving at different speeds as it rolls. Thus, there are opposing forces and sliding motions at each ball/race contact. Overall, these cause bearing drag. Roller bearings are

360-462: A ball bearing or a spherical roller bearing. As in all radial bearings, the outer load is continuously re-distributed among the rollers. Often fewer than half of the total number of rollers carry a significant portion of the load. The animation on the right shows how a static radial load is supported by the bearing rollers as the inner ring rotates. Spherical roller bearings have an outer race with an internal spherical shape. The rollers are thicker in

450-470: A bearing assembly are also affected by the speed of operation: rolling-element bearings may spin over 100,000 rpm, and the principal load in such a bearing may be momentum rather than the applied load. Smaller rolling elements are lighter and thus have less momentum, but smaller elements also bend more sharply where they contact the race, causing them to fail more rapidly from fatigue. Maximum rolling-element bearing speeds are often specified in 'nD m ', which

540-581: A better ability to record a range of brightness than slide/transparency film or digital. Digital should be considered to be the reverse of print film, with a good latitude in the shadow range, and a narrow one in the highlight area; in contrast to film's large highlight latitude, and narrow shadow latitude. Slide/Transparency film has a narrow latitude in both highlight and shadow areas, requiring greater exposure accuracy. Negative film's latitude increases somewhat with high ISO material, in contrast digital tends to narrow on latitude with high ISO settings. Areas of

630-458: A built-in light meter , or multiple point meters interpreted by a built-in computer, see metering mode . Negative and print film tends to bias for exposing for the shadow areas (film dislikes being starved of light), with digital favouring exposure for highlights. See latitude below. Latitude is the degree by which one can over, or under expose an image, and still recover an acceptable level of quality from an exposure. Typically negative film has

720-488: A cage, which is then placed between the two flat surfaces; a common example is drawer-support hardware. Roller-element bearing for a shaft use bearing balls in a groove designed to recirculate them from one end to the other as the bearing moves; as such, they are called linear ball bearings or recirculating bearings . Rolling-element bearings often work well in non-ideal conditions, but sometimes minor problems cause bearings to fail quickly and mysteriously. For example, with

810-400: A greater tonality range over conventional methods by varying the contrast of the film to fit the print contrast capability. Digital cameras can achieve similar results ( high dynamic range ) by combining several different exposures (varying shutter or diaphragm) made in quick succession. Today, most cameras automatically determine the correct exposure at the time of taking a photograph by using

900-500: A longer lifetime for a correctly-used bearing below its design load, or also as the increased rate by which lifetime is shortened when overloaded. This model was recognised to have become inaccurate for modern bearings. Particularly owing to improvements in the quality of bearing steels, the mechanisms for how failures develop in the 1924 model are no longer as significant. By the 1990s, real bearings were found to give service lives up to 14 times longer than those predicted. An explanation

990-472: A loss of highlight detail, that is, when important bright parts of an image are "washed out" or effectively all white, known as "blown-out highlights" or " clipped whites ". A photograph may be described as underexposed when it has a loss of shadow detail, that is, when important dark areas are "muddy" or indistinguishable from black, known as "blocked-up shadows" (or sometimes "crushed shadows", "crushed blacks", or "clipped blacks", especially in video). As

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1080-457: A matching viewfinder. The viewfinder had seven elements, more than the lens itself. The field of view was so wide the camera was bundled with an accessory pistol grip that screws into the tripod socket to prevent inadvertent inclusion of the photographer's hands in the image. To compensate for vignetting, a radially-graduated neutral density filter was included. The Hologon was built from 1969 to 1972, when Zeiss Ikon ceased camera production. Like

1170-577: A number of smaller 'satellite' gears which revolve around the center of the bearing along a track on the outsides of the internal and satellite gears, and on the inside of the external gear. The downside to this bearing is manufacturing complexity. Tapered roller bearings use conical rollers that run on conical races. Most roller bearings only take radial or axial loads, but tapered roller bearings support both radial and axial loads, and generally can carry higher loads than ball bearings due to greater contact area. Tapered roller bearings are used, for example, as

1260-508: A photo where information is lost due to extreme brightness are described as having "blown-out highlights" or "flared highlights". In digital images this information loss is often irreversible, though small problems can be made less noticeable using photo manipulation software . Recording to RAW format can correct this problem to some degree, as can using a digital camera with a better sensor. Film can often have areas of extreme overexposure but still record detail in those areas. This information

1350-407: A reciprocally smaller aperture is required to reduce the amount of light hitting the film to obtain the same exposure. For example, the photographer may prefer to make his sunny-16 shot at an aperture of f /5.6 (to obtain a shallow depth of field). As f /5.6 is 3 stops "faster" than f /16 , with each stop meaning double the amount of light, a new shutter speed of (1/125)/(2·2·2) = 1/1000 s

1440-458: A scene with strong or harsh lighting, the ratio between highlight and shadow luminance values may well be larger than the ratio between the film's maximum and minimum useful exposure values. In this case, adjusting the camera's exposure settings (which only applies changes to the whole image, not selectively to parts of the image) only allows the photographer to choose between underexposed shadows or overexposed highlights; it cannot bring both into

1530-971: A shaft in a much larger hole, and spheres or cylinders called "rollers" tightly fill the space between the shaft and hole. As the shaft turns, each roller acts as the logs in the above example. However, since the bearing is round, the rollers never fall out from under the load. Rolling-element bearings have the advantage of a good trade-off between cost, size, weight, carrying capacity, durability, accuracy, friction, and so on. Other bearing designs are often better on one specific attribute, but worse in most other attributes, although fluid bearings can sometimes simultaneously outperform on carrying capacity, durability, accuracy, friction, rotation rate and sometimes cost. Only plain bearings are used as widely as rolling-element bearings. Common mechanical components where they are widely used are – automotive, industrial, marine, and aerospace applications. They are products of great necessity for modern technology. The rolling element bearing

1620-414: A shutter speed of 1/100 of a second. This is called the sunny 16 rule : at an aperture of f /16 on a sunny day, a suitable shutter speed will be one over the film speed (or closest equivalent). A scene can be exposed in many ways, depending on the desired effect a photographer wishes to convey. An important principle of exposure is reciprocity . If one exposes the film or sensor for a longer period,

1710-422: A specified region. An "exposure" is a single shutter cycle . For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated photometric exposure ( H v ) is the same so long as the total exposure time is the same. Radiant exposure of

1800-457: A split image inside of a micro-prism. A thumb-wheel on the camera controls the lens aperture, and the value is shown in a window on top of the centrally located meter cell (the Cyclops window ). The shutter speed dial is lifted and rotated to set the film speed. The aperture in the interchangeable automatic lens closes when the shutter release is depressed and reopens when the camera is wound on for

1890-444: A stationary (non-rotating) load, small vibrations can gradually press out the lubricant between the races and rollers or balls ( false brinelling ). Without lubricant the bearing fails, even though it is not rotating and thus is apparently not being used. For these sorts of reasons, much of bearing design is about failure analysis. Vibration based analysis can be used for fault identification of bearings. There are three usual limits to

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1980-530: A waist-level finder. The Contarex Professional or P (catalog 10.2700) replaced the Special with updated cosmetics, and like the Special , also deleted the internal light meter. It was built from 1966 to 1967. Unlike the Special , the Professional was equipped with a fixed eye-level pentaprism viewfinder. The Professional was the first model released in the second generation of Contarex SLR cameras (spanning

2070-587: A working knowledge of exposure values , the APEX system and/or the Zone System . A camera in automatic exposure or autoexposure (usually initialized as AE ) mode automatically calculates and adjusts exposure settings to match (as closely as possible) the subject's mid-tone to the mid-tone of the photograph. For most cameras, this means using an on-board TTL exposure meter . Aperture priority (commonly abbreviated as A , or Av for aperture value ) mode gives

2160-416: Is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races . The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding . One of the earliest and best-known rolling-element bearings are sets of logs laid on the ground with a large stone block on top. As

2250-474: Is a prominent wheel for the photographer's right index finger, on the top corner of the lens mount escutcheon, which controls aperture. This detail was reminiscent of the focusing wheel on pre-war Contax rangefinder cameras, and was carried throughout the Contarex SLR line. Shutter speeds are controlled by a dial coaxial with and at the base of the film winding lever / exposure counter / shutter release button at

2340-418: Is a special type of roller bearing which uses long, thin cylindrical rollers resembling needles. Often the ends of the rollers taper to points, and these are used to keep the rollers captive, or they may be hemispherical and not captive but held by the shaft itself or a similar arrangement. Since the rollers are thin, the outside diameter of the bearing is only slightly larger than the hole in the middle. However,

2430-545: Is based on it. The concept of fatigue limit, and thus ISO 281:2007, remains controversial, at least in the US. In 2015, the SKF Generalized Bearing Life Model (GBLM) was introduced. In contrast to previous life models, GBLM explicitly separates surface and subsurface failure modes – making the model flexible to accommodate several different failure modes. Modern bearings and applications show fewer failures, but

2520-418: Is controlled in a camera by shutter speed , and the illuminance depends on the lens aperture and the scene luminance . Slower shutter speeds (exposing the medium for a longer period of time), greater lens apertures (admitting more light), and higher-luminance scenes produce greater exposures. An approximately correct exposure will be obtained on a sunny day using ISO 100 film, an aperture of f /16 and

2610-419: Is instead related to in statistical terms, referring to populations of bearings. All information with regard to load ratings is then based on the life that 90% of a sufficiently large group of apparently identical bearings can be expected to attain or exceed. This gives a clearer definition of the concept of bearing life, which is essential to calculate the correct bearing size. Life models can thus help to predict

2700-435: Is intended to allow the photographer to simply offset the exposure level from the internal meter's estimate of appropriate exposure. Frequently calibrated in stops, also known as EV units , a "+1" exposure compensation setting indicates one stop more (twice as much) exposure and "–1" means one stop less (half as much) exposure. Exposure compensation is particularly useful in combination with auto-exposure mode, as it allows

2790-429: Is lost during capture. The photographer may carefully overexpose or underexpose the photograph to eliminate "insignificant" or "unwanted" detail; to make, for example, a white altar cloth appear immaculately clean, or to emulate the heavy, pitiless shadows of film noir . However, it is technically much easier to discard recorded information during post processing than to try to 're-create' unrecorded information. In

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2880-472: Is measured on a scale published by the International Organization for Standardization (ISO). Faster film, that is, film with a higher ISO rating, requires less exposure to make a readable image. Digital cameras usually have variable ISO settings that provide additional flexibility. Exposure is a combination of the length of time and the illuminance at the photosensitive material. Exposure time

2970-460: Is needed. Rolling-element bearings are often used for axles due to their low rolling friction. For light loads, such as bicycles, ball bearings are often used. For heavy loads and where the loads can greatly change during cornering, such as cars and trucks, tapered rolling bearings are used. Linear motion roller-element bearings are typically designed for either shafts or flat surfaces. Flat surface bearings often consist of rollers and are mounted in

3060-407: Is needed. Once the photographer has determined the exposure, aperture stops can be traded for halvings or doublings of speed, within limits. The true characteristic of most photographic emulsions is not actually linear (see sensitometry ), but it is close enough over the exposure range of about 1 second to 1/1000 of a second. Outside of this range, it becomes necessary to increase the exposure from

3150-528: Is set on the camera aperture wheel. The Contarex lens mount takes only Contarex lenses and accessories. The lenses Zeiss designed and manufactured for the Contarex cameras have been called "the best 35 mm lenses that have ever been made". According to noted Leica historian and reviewer Erwin Puts, "Zeiss designers gave the most attention to flatness of field and the reduction of astigmatism. [...] The characteristics of

3240-465: Is that bearing life is finite, and reduces by a cube power of the ratio between design load and applied load. This model was developed in 1924, 1947 and 1952 work by Arvid Palmgren and Gustaf Lundberg in their paper Dynamic Capacity of Rolling Bearings . The model dates from 1924, the values of the constant p {\displaystyle p} from the post-war works. Higher p {\displaystyle p} values may be seen as both

3330-410: Is that, like a cylindrical roller, they do not locate axially. CARB bearings are typically used in pairs with a locating bearing, such as a spherical roller bearing . This non-locating bearing can be an advantage, as it can be used to allow a shaft and a housing to undergo thermal expansion independently. Toroidal roller bearings were introduced in 1995 by SKF as "CARB bearings". The inventor behind

3420-420: Is the ball bearing . The bearing has inner and outer races between which balls roll. Each race features a groove usually shaped so the ball fits slightly loose. Thus, in principle, the ball contacts each race across a very narrow area. However, a load on an infinitely small point would cause infinitely high contact pressure. In practice, the ball deforms (flattens) slightly where it contacts each race much as

3510-465: Is the Carl Zeiss Planar 1:2 f=50mm in bright aluminium finish with a chrome 49 mm thread filter ring and an outer bayonet for Zeiss-Ikon filters. The lens focuses to 0.3 m (1 ft 0 in), which is closer than the usual 0.5 m (1 ft 8 in) for a normal lens. The focusing helical is remarkably smooth and precise. There is no aperture ring on the Contarex lens itself. It

3600-470: Is the life that 90% of bearings can be expected to reach or exceed. The median or average life, sometimes called Mean Time Between Failure (MTBF), is about five times the calculated basic rating life. Several factors, the ' ASME five factor model', can be used to further adjust the L 10 {\displaystyle L_{10}} life depending upon the desired reliability, lubrication, contamination, etc. The major implication of this model

3690-479: Is the presence of water in the lubrication oil. Online water-in-oil monitors have been introduced in recent years to monitor the effects of both particles and the presence of water in oil and their combined effect. Metric rolling-element bearings have alphanumerical designations, defined by ISO 15 , to define all of the physical parameters. The main designation is a seven digit number with optional alphanumeric digits before or after to define additional parameters. Here

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3780-524: Is the product of the mean diameter (in mm) and the maximum RPM. For angular contact bearings nD m s over 2.1 million have been found to be reliable in high performance rocketry applications. There are also many material issues: a harder material may be more durable against abrasion but more likely to suffer fatigue fracture, so the material varies with the application, and while steel is most common for rolling-element bearings, plastics, glass, and ceramics are all in common use. A small defect (irregularity) in

3870-582: Is to estimate the subject's mid-tone luminance and indicate the camera exposure settings required to record this as a mid-tone. In order to do this it has to make a number of assumptions which, under certain circumstances, will be wrong. If the exposure setting indicated by an exposure meter is taken as the "reference" exposure, the photographer may wish to deliberately overexpose or underexpose in order to compensate for known or anticipated metering inaccuracies. Cameras with any kind of internal exposure meter usually feature an exposure compensation setting which

3960-451: The Bullseye with the same updated cosmetics of the Professional . It was built from 1967 to 1972, when Zeiss Ikon ceased camera production. The internal meter for second-generation Contarex models so equipped ( Super and Super Electronic ) used a CdS through-the-lens photoresistor , rather than the external selenium meter of the first-generation Bullseye . The meter power switch is on

4050-421: The Professional , Super , and Electronic ); the updated appearance included replacing the script "Contarex" logo of the first generation ( Bullseye and Special ) with a blocky typeface set on a black background on the front of the pentaprism viewfinder housing. In addition, the film speed setting/reminder dial was moved to be coaxial with the rewind knob. The Contarex Super or S (catalog 10.2600) succeeded

4140-409: The earliest known type of rolling-element-bearing, dating back to at least 40 BC. Common roller bearings use cylinders of slightly greater length than diameter. Roller bearings typically have a higher radial load capacity than ball bearings, but a lower capacity and higher friction under axial loads. If the inner and outer races are misaligned, the bearing capacity often drops quickly compared to either

4230-459: The "dimensional series" of the bearing. Autoexposure In photography , exposure is the amount of light per unit area reaching a frame of photographic film or the surface of an electronic image sensor . It is determined by shutter speed , lens f-number , and scene luminance . Exposure is measured in units of lux - seconds (symbol lx ⋅ s), and can be computed from exposure value (EV) and scene luminance in

4320-460: The Contarex lenses are reminiscent of the Hasselblad lenses. Stopped down a bit they exhibit a remarkable finesse of gradation and depth. They may not be the sharpest lenses ever, but the rendition of shape outlines and surface details is most pleasing and subtle like a poem." Rolling-element bearing In mechanical engineering , a rolling-element bearing , also known as a rolling bearing ,

4410-539: The SE was capable of aperture-priority autoexposure . The Contarex Hologon was a fixed-lens camera that used the same stripped-down second-generation chassis as the microscope camera, which removed the reflex mirror and viewfinder mechanisms, featuring mechanically-controlled shutter speeds ranging from 1– 1 ⁄ 500 s plus "B"ulb and "T"imer. It was purpose-built to carry the fixed-focus, fixed-aperture, three-element Hologon 15 mm f /8 ultra wide angle lens and

4500-503: The Super and Electronic, a few cameras were assembled later. Some Hologon cameras have been disassembled for their lenses, which were fitted with Leica M bayonet mounts. The Contarex Microscope used the chassis of the Super , stripped of its viewfinder and mirror assembly. Shutter speeds for the focal plane shutter range from 1– 1 ⁄ 500  sec with B and T settings. The standard lens

4590-580: The U.S. Space Shuttle which could not be adequately isolated from the liquid oxygen being pumped. All lubricants reacted with the oxygen, leading to fires and other failures. The solution was to lubricate the bearing with the oxygen. Although liquid oxygen is a poor lubricant, it was adequate, since the service life of the pump was just a few hours. The operating environment and service needs are also important design considerations. Some bearing assemblies require routine addition of lubricants, while others are factory sealed , requiring no further maintenance for

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4680-592: The ability to take on axial loading and radial loading and how it does this is by using a conical structure enabling the elements to roll diagonally. Barrel -  Provides assistance to high radial socks loads that cause misalignment and uses its shape and size for compensation. Needle - Varying in size, diameters, and materials these types of bearings are best suited for helping reduce weight as well as smaller cross sections application, typically higher load capacity than ball bearings and rigid shaft applications. A particularly common kind of rolling-element bearing

4770-422: The adjacent image shows, these terms are technical ones rather than artistic judgments; an overexposed or underexposed image may be "correct" in the sense that it provides the effect that the photographer intended. Intentionally over- or underexposing (relative to a standard or the camera's automatic exposure) is casually referred to as " exposing to the right " or "exposing to the left" respectively, as these shift

4860-402: The appropriate spectral sensitivity , the exposure is still measured in radiometric units (joules per square meter), rather than photometric units (weighted by the nominal sensitivity of the human eye). Only in this appropriately weighted case does the H measure the effective amount of light falling on the film, such that the characteristic curve will be correct independent of the spectrum of

4950-590: The bearing was the engineer Magnus Kellström. The configuration of the races determine the types of motions and loads that a bearing can best support. A given configuration can serve multiple of the following types of loading. Thrust bearings are used to support axial loads, such as vertical shafts. Common designs are Thrust ball bearings , spherical roller thrust bearings , tapered roller thrust bearings or cylindrical roller thrust bearings. Also non-rolling-element bearings such as hydrostatic or magnetic bearings see some use where particularly heavy loads or low friction

5040-403: The bearing. For example, on radial thrust bearings the digits define the contact angle, or the presence of seals on any bearing type. The seventh digit defines the "width series", or thickness, of the bearing. The width series, defined from lightest to heaviest, is: 7, 8, 9, 0, 1 (extra light series), 2 (light series), 3 (medium series), 4 (heavy series). The third digit and the seventh digit define

5130-430: The board consisting of the outer and inner track, a central bore, a retainer to keep the rolling elements from clashing into one another or seizing the bearing movement, and the rolling elements themselves. The internal rolling  components may differ in design due to their intended purpose of application of the bearing.  The main five types of bearings are Ball, Cylindrical, Tapered, Barrel, and Needle. Ball -

5220-471: The calculated value to account for this characteristic of the emulsion. This characteristic is known as reciprocity failure . The film manufacturer's data sheets should be consulted to arrive at the correction required, as different emulsions have different characteristics. Digital camera image sensors can also be subject to a form of reciprocity failure. The Zone System is another method of determining exposure and development combinations to achieve

5310-485: The digits will be defined as: 7654321. Any zeros to the left of the last defined digit are not printed; e.g. a designation of 0007208 is printed 7208. Digits one and two together are used to define the inner diameter (ID), or bore diameter, of the bearing. For diameters between 20 and 495 mm, inclusive, the designation is multiplied by five to give the ID; e.g. designation 08 is a 40 mm ID. For inner diameters less than 20

5400-459: The effect the photographer intended. A more technical approach recognises that a photographic film (or sensor) has a physically limited useful exposure range , sometimes called its dynamic range . If, for any part of the photograph, the actual exposure is outside this range, the film cannot record it accurately. In a very simple model, for example, out-of-range values would be recorded as "black" (underexposed) or "white" (overexposed) rather than

5490-510: The effects of lubrication, contamination, and race surface properties, which together influence the stress distribution in the rolling contact. In 2019, the Generalized Bearing Life Model was relaunched. The updated model offers life calculations also for hybrid bearings, i.e. bearings with steel rings and ceramic (silicon nitride) rolling elements. Even if the 2019 GBLM release was primarily developed to realistically determine

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5580-421: The failures that do occur are more linked to surface stresses. By separating surface from the subsurface, mitigating mechanisms can more easily be identified. GBLM makes use of advanced tribology models to introduce a surface distress failure mode function, obtained from the evaluation of surface fatigue. For the subsurface fatigue, GBLM uses the classical Hertzian rolling contact model. With all this, GBLM includes

5670-547: The first NASA extra vehicular activity ( EVA ) on June 3, 1965, during the flight of Gemini 4 . Geoffrey Crawley published an extensive review of the Contarex Super and lens system in 1970 for the British Journal of Photography . The Contarex I , aka Bullseye (catalog 10.2401), was built between 1959 and 1966. It was the first 35mm SLR camera with a focal plane shutter that provides direct light meter coupling to

5760-399: The following designations are used: 00 = 10 mm ID, 01 = 12 mm ID, 02 = 15 mm ID, and 03 = 17 mm ID. The third digit defines the "diameter series", which defines the outer diameter (OD). The diameter series, defined in ascending order, is: 0, 8, 9, 1, 7, 2, 3, 4, 5, 6. The fourth digit defines the type of bearing: The fifth and sixth digit define structural modifications to

5850-512: The histogram of the image to the right or left. In manual mode, the photographer adjusts the lens aperture and/or shutter speed to achieve the desired exposure. Many photographers choose to control aperture and shutter independently because opening up the aperture increases exposure, but also decreases the depth of field , and a slower shutter increases exposure but also increases the opportunity for motion blur . "Manual" exposure calculations may be based on some method of light metering with

5940-466: The idea of a 'fatigue limit' entered bearing lifetime calculations. If the bearing was not loaded beyond this limit, its theoretical lifetime would be limited only by external factors, such as contamination or a failure of lubrication. A new model of bearing life was put forward by FAG and developed by SKF as the Ioannides-Harris model. ISO 281:2000 first incorporated this model and ISO 281:2007

6030-416: The life of the mechanical assembly. Although seals are appealing, they increase friction, and in a permanently sealed bearing the lubricant may become contaminated by hard particles, such as steel chips from the race or bearing, sand, or grit that gets past the seal. Contamination in the lubricant is abrasive and greatly reduces the operating life of the bearing assembly. Another major cause of bearing failure

6120-483: The lifetime or load capacity of a bearing: abrasion, fatigue and pressure-induced welding. Although there are many other apparent causes of bearing failure, most can be reduced to these three. For example, a bearing which is run dry of lubricant fails not because it is "without lubricant", but because lack of lubrication leads to fatigue and welding, and the resulting wear debris can cause abrasion. Similar events occur in false brinelling damage. In high speed applications,

6210-654: The light. Many photographic materials are also sensitive to "invisible" light, which can be a nuisance (see UV filter and IR filter ), or a benefit (see infrared photography and full-spectrum photography ). The use of radiometric units is appropriate to characterize such sensitivity to invisible light. In sensitometric data, such as characteristic curves, the log exposure is conventionally expressed as log 10 ( H ). Photographers more familiar with base-2 logarithmic scales (such as exposure values ) can convert using log 2 ( H ) ≈ 3.32 log 10 ( H ) . "Correct" exposure may be defined as an exposure that achieves

6300-545: The material is often responsible for bearing failure; one of the biggest improvements in the life of common bearings during the second half of the 20th century was the use of more homogeneous materials, rather than better materials or lubricants (though both were also significant). Lubricant properties vary with temperature and load, so the best lubricant varies with application. Although bearings tend to wear out with use, designers can make tradeoffs of bearing size and cost versus lifetime. A bearing can last indefinitely—longer than

6390-434: The middle and thinner at the ends. Spherical roller bearings can thus accommodate both static and dynamic misalignment. However, spherical rollers are difficult to produce and thus expensive, and the bearings have higher friction than an ideal cylindrical or tapered roller bearing since there will be a certain amount of sliding between rolling elements and races. Gear bearings are similar to epicyclic gearing . They consist of

6480-472: The next exposure. Due to the limited meter range, not every camera setting combination is possible to accommodate on the Contarex I exposure meter. The Contarex Special (catalog 10.2500) was equivalent to the Bullseye , but the Special omitted the selenium cell meter. It was built from 1960 to 1966. The viewfinder of the Special is removable and two styles were available: a pentaprism, for eye-level use, or

6570-465: The oil flow also reduces the bearing metal temperature by convection. The oil becomes the heat sink for the friction losses generated by the bearing. ISO has categorised bearing failures into a document Numbered ISO 15243. The life of a rolling bearing is expressed as the number of revolutions or the number of operating hours at a given speed that the bearing is capable of enduring before the first sign of metal fatigue (also known as spalling ) occurs on

6660-475: The opposite side of the lens mount escutcheon from the aperture setting wheel. The Contarex Super Electronic or SE (catalog 10.2800) used the chassis of the Super , fitted with an electronically-controlled shutter. It was built from 1968 to 1972, when Zeiss Ikon ceased camera production. A few cameras were assembled later, with the Carl Zeiss brand instead of Zeiss Ikon. With a "photoelectric timer" attachment,

6750-583: The performance of a bearing more realistically. The prediction of bearing life is described in ISO 281 and the ANSI /American Bearing Manufacturers Association Standards 9 and 11. The traditional life prediction model for rolling-element bearings uses the basic life equation: L 10 = ( C / P ) p {\displaystyle L_{10}=(C/P)^{p}} Where: Basic life or L 10 {\displaystyle L_{10}}

6840-477: The photographer manual control of the aperture, whilst the camera automatically adjusts the shutter speed to achieve the exposure specified by the TTL meter. Shutter priority (often abbreviated as S , or Tv for time value ) mode gives manual shutter control, with automatic aperture compensation. In each case, the actual exposure level is still determined by the camera's exposure meter. The purpose of an exposure meter

6930-401: The photographer to bias the exposure level without resorting to full manual exposure and losing the flexibility of auto exposure. On low-end video camcorders, exposure compensation may be the only manual exposure control available. An appropriate exposure for a photograph is determined by the sensitivity of the medium used. For photographic film, sensitivity is referred to as film speed and

7020-471: The photographer's right hand. Contarex SLRs featured a slip-off back, which could be removed and replaced by an interchangeable magazine back (catalog 20.0304). This magazine back concept was shared with the Contaflex SLR , although Contarex magazine backs are wider and physically incompatible with Contaflex cameras and vice versa. A custom modified Contarex Special was used by astronaut Ed White during

7110-406: The precisely graduated shades of colour and tone required to describe "detail". Therefore, the purpose of exposure adjustment (and/or lighting adjustment) is to control the physical amount of light from the subject that is allowed to fall on the film, so that 'significant' areas of shadow and highlight detail do not exceed the film's useful exposure range. This ensures that no 'significant' information

7200-611: The race of the inner or outer ring, or on a rolling element. Calculating the endurance life of bearings is possible with the help of so-called life models. More specifically, life models are used to determine the bearing size – since this must be sufficient to ensure that the bearing is strong enough to deliver the required life under certain defined operating conditions. Under controlled laboratory conditions, however, seemingly identical bearings operating under identical conditions can have different individual endurance lives. Thus, bearing life cannot be calculated based on specific bearings, but

7290-415: The rest of the machine—if it is kept cool, clean, lubricated, is run within the rated load, and if the bearing materials are sufficiently free of microscopic defects. Cooling, lubrication, and sealing are thus important parts of the bearing design. The needed bearing lifetime also varies with the application. For example, Tedric A. Harris reports in his Rolling Bearing Analysis on an oxygen pump bearing in

7380-448: The shutter-, aperture-, and film speed -settings; they are interconnected by cords. An aperture simulator for the exposure meter in the Cyclops window uses an iris in front of the selenium meter cell. To set the proper exposure, the meter needle is aligned with an index triangle, which is visible both in a top plate window and to the right side of the viewfinder. The camera also has an interchangeable focusing screen which is, by default,

7470-418: The simplest following the basic principles with minimal design intention. Important to note the ability for more seizures is likely due to the freedom of the track design.   Cylindrical - For single axis movement for straight directional movement. The shape allows for more surface area to be in contact adding in moving more weight with less force at a greater distance. Tapered -  Primarily focused on

7560-494: The small-diameter rollers must bend sharply where they contact the races, and thus the bearing fatigues relatively quickly. CARB bearings are toroidal roller bearings and similar to spherical roller bearings , but can accommodate both angular misalignment and also axial displacement. Compared to a spherical roller bearing, their radius of curvature is longer than a spherical radius would be, making them an intermediate form between spherical and cylindrical rollers. Their limitation

7650-409: The stone is pulled, the logs roll along the ground with little sliding friction . As each log comes out the back, it is moved to the front where the block then rolls on to it. It is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See " bearings " for more on the historical development of bearings. A rolling element rotary bearing uses

7740-524: The useful exposure range at the same time. Methods for dealing with this situation include: using what is called fill lighting to increase the illumination in shadow areas; using a graduated neutral-density filter , flag, scrim, or gobo to reduce the illumination falling upon areas deemed too bright; or varying the exposure between multiple, otherwise identical, photographs ( exposure bracketing ) and then combining them afterwards in an HDRI process. A photograph may be described as overexposed when it has

7830-458: The wheel bearings of most wheeled land vehicles. The downsides to this bearing is that due to manufacturing complexities, tapered roller bearings are usually more expensive than ball bearings; and additionally under heavy loads the tapered roller is like a wedge and bearing loads tend to try to eject the roller; the force from the collar which keeps the roller in the bearing adds to bearing friction compared to ball bearings. The needle roller bearing

7920-431: The working life of hybrid bearings, the concept can also be used for other products and failure modes. All parts of a bearing are subject to many design constraints. For example, the inner and outer races are often complex shapes, making them difficult to manufacture. Balls and rollers, though simpler in shape, are small; since they bend sharply where they run on the races, the bearings are prone to fatigue. The loads within

8010-582: Was developed from a firm foundation that was built over thousands of years. The concept emerged in its primitive form in Roman times . After a long inactive period in the Middle Ages, it was revived during the Renaissance by Leonardo da Vinci , and developed steadily in the seventeenth and eighteenth centuries. Design description Bearings, especially rolling element bearings are designed in similar fashion across

8100-667: Was put forward based on fatigue life ; if the bearing was loaded to never exceed the fatigue strength , then the Lundberg-Palmgren mechanism for failure by fatigue would simply never occur. This relied on homogeneous vacuum-melted steels , such as AISI 52100 , that avoided the internal inclusions that had previously acted as stress risers within the rolling elements, and also on smoother finishes to bearing tracks that avoided impact loads. The p {\displaystyle p} constant now had values of 4 for ball and 5 for roller bearings. Provided that load limits were observed,

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