The Canon AV-1 is a 35 mm single-lens reflex camera with an FD lens mount, introduced by Canon Inc. in 1979. The AV-1 was similar to the 1976 AE-1 but provided aperture priority autoexposure rather than the AE-1's shutter speed priority AE; the camera is not capable of manual exposure. Canon's international distributors in the United States, had clamored for such a camera because competing brands offered aperture-priority cameras and some preferred it; the AV in the name referred to the type of autoexposure. When this camera appeared, a new range of FD lenses was introduced, with instant mounting/unmounting of the lens; this was called the New FD mount and did away with the older type of mounting ring, fitted on to the rear of the lens and was awkward to use and needed two hands, to a newer, easier system whereby the user lined up the red dot on the lens, with the red dot on the camera and turned the whole lens clockwise until it clicked into place. All the other AE-1 accessories fit the AV-1.
Media related to Canon AV-1 at Wikimedia Commons Canon Inc. Canon AV-1 manual. Retrieved December 27, 2015. Canon AV-1 Camera at Photography of Malaysia
In photography, through-the-lens metering refers to a feature of cameras whereby the intensity of light reflected from the scene is measured through the lens. In some cameras various TTL metering modes can be selected; this information can be used to set the optimal film or image sensor exposure, it can be used to control the amount of light emitted by a flash unit connected to the camera. Through-the-lens metering is most associated with single-lens reflex cameras. In most film and digital SLRs, the light sensor for exposure metering are incorporated into the pentaprism or pentamirror, the mechanism by which a SLR allows the viewfinder to see directly through the lens; as the mirror is flipped up, no light can reach there during exposure, the necessary amount of exposure needs to be determined before the actual exposure. These light sensors could traditionally be used for ambient light TTL metering only. In newer SLRs as well as in all DSLRs, they can be utilized for preflash TTL metering, where the metering is carried out before the mirror flips up using a small preflash of known intensity and the necessary amount of flash light is extrapolated from the reflected flash light measured by the metering cells in the roof of the camera and is applied during the exposure without any possible real-time feedback.
There were a few sophisticated film SLRs including the Olympus OM-2, the Pentax LX, the Nikon F3, the Minolta 9000, where metering cells located at the bottom of the mirror box were used for ambient light metering, depending on model either instead or in addition to metering cells in the roof of the camera. Depending on model, the light was reflected down there either by a secondary mirror behind the half-transparent main mirror, a special reflective coating of the first shutter curtain, the surface of the film itself, or combinations thereof. One of the advantages of this approach is that the measuring result requires no adjustments when changing focusing screens or viewfinders; some of the cameras using this configuration are immune against measurement errors caused by light reaching the metering cells at larger angles, for example with shift/tilt lenses. Metering cells located at the bottom of the mirror box using light reflected off the film are used in all film SLRs supporting the classical form of real-time TTL flash metering.
Some early Pentax DSLRs could use this same configuration for TTL flash metering as well, but since the reflectance properties of image sensors differ from those of film, this method proved to be unreliable in practice. Therefore, digital SLR cameras don't support any real-time TTL flash metering and must use preflash metering instead; the ambient and flash light metering is carried out by a metering module located in the roof of the camera. Digital SLRs supporting live view or video will use the read out of the image sensor itself for exposure metering in these modes; this applies to Sony's SLT digital cameras, which use the image sensor for exposure metering all the time. Up to the time of this writing, no digital SLR or SLT camera on the market supported any form of real-time TTL flash metering using the image sensor. However, it can be expected that such methods will be introduced as image sensor technology progresses, given the advantages of metering with real-time feedback and without preflash.
TTL metering systems have been incorporated into other types of cameras as well. Most digital "point-and-shoot cameras" use TTL metering, performed by the imaging sensor itself. In many advanced modern cameras multiple'segments' are used to acquire the amount of light in different places of the picture. Depending on the mode the photographer has selected, this information is used to set the exposure. With a simple spot meter, a single spot on the picture is selected; the camera sets the exposure. On some modern SLR systems the spot metering area or zone can be coupled to the actual focusing area selected offering more flexibility and less need to use exposure lock systems. With multiple segment metering, the values of the different segments are combined and weighted to set the correct exposure. Implementations of these metering modes vary between cameras and manufacturers, making it difficult to predict how a scene will be exposed when switching cameras. In the 1970s Olympus marketed the OM-2 camera.
In OTF metering used by Olympus, metering was performed in one of two ways — or a combination of both — depending upon the shutter speed in use. In the OM-2's Auto Dynamic Metering system the first shutter curtain had the lens-facing side coated with a computer generated pattern of white blocks to emulate an average scene; as the mirror flipped-up the metering cell in the base of the mirror box measured the light reflected from the subject bouncing off this pattern of blocks. The timing of the release of the second curtain was adjusted in real time during the actual exposure; as the shutter speed increased, the actual light reflecting off the film surface was measured and the timing of the second curtain's release adjusted accordingly. This gave cameras equipped with this system the ability to adjust to changes in lighting during the actual exposure, useful for specialist applications such as photomicrography and astronomical photography. Leica used a variation of this system, as did Pentax with their Integrated Direct Metering in the LX camera.
A variation of this "OTF" system was used on early
Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid, it occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound, easy to isolate and purify, it is the principal source of cadmium for all commercial applications, its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century. Cadmium sulfide can be prepared by the precipitation from soluble cadmium salts with sulfide ion; this reaction has been used for qualitative inorganic analysis. The preparative route and the subsequent treatment of the product, affects the polymorphic form, produced, it has been asserted. Pigment production involves the precipitation of CdS, the washing of the solid precipitate to remove soluble cadmium salts followed by calcination to convert it to the hexagonal form followed by milling to produce a powder.
When cadmium sulfide selenides are required the CdSe is co-precipitated with CdS and the cadmium sulfoselenide is created during the calcination step. Cadmium sulfide is sometimes associated with sulfate reducing bacteria. Special methods are used to produce films of CdS as components in some photoresistors and solar cells. In the chemical bath deposition method, thin films of CdS have been prepared using thiourea as the source of sulfide anions and an ammonium buffer solution to control pH: Cd2+ + H2O + 2CS + 2 NH3 → CdS + 2CO + 2 NH4+Cadmium sulfide can be produced using metalorganic vapour phase epitaxy and MOCVD techniques by the reaction of dimethylcadmium with diethyl sulfide: Cd2 + Et2S → CdS + CH3CH3 + C4H10Other methods to produce films of CdS include Sol gel techniques Sputtering Electrochemical deposition Spraying with precursor cadmium salt, sulfur compound and dopant Screen printing using a slurry containing dispersed CdS Cadmium sulfide can be dissolved in acids. CdS + 2 HCl → CdCl2 + H2SWhen solutions of sulfide containing dispersed CdS particles are irradiated with light hydrogen gas is generated: H2S → H2 + S ΔHf = +9.4 kcal/molThe proposed mechanism involves the electron/hole pairs created when incident light is absorbed by the cadmium sulfide followed by these reacting with water and sulfide: Production of an electron hole pair CdS + hν → e− + hole+ Reaction of electron 2e− + 2H2O → H2 + 2OH− Reaction of hole 2hole+ + S2− → S Cadmium sulfide has, like zinc sulfide, two crystal forms.
The more stable hexagonal wurtzite structure and the cubic zinc blende structure. In both of these forms the cadmium and sulfur atoms are four coordinate. There is a high pressure form with the NaCl rock salt structure. Cadmium sulfide is a direct band gap semiconductor; the magnitude of its band gap means. As well as this obvious property other properties result: the conductivity increases when irradiated, when combined with a p-type semiconductor it forms the core component of a photovoltaic cell and a CdS/Cu2S solar cell was one of the first efficient cells to be reported when doped with for example Cu+ and Al3+ CdS luminesces under electron beam excitation and is used as phosphor both polymorphs are piezoelectric and the hexagonal is pyroelectric electroluminescence CdS crystal can act as a solid state laser In thin-film form, CdS can be combined with other layers for use in certain types of solar cells. CdS was one of the first semiconductor materials to be used for thin-film transistors.
However interest in compound semiconductors for TFTs waned after the emergence of amorphous silicon technology in the late 1970s. Thin films of CdS can be piezoelectric and have been used as transducers which can operate at frequencies in the GHz region. Nanoribbons of CdS show a net cooling due annihilation of phonons, during anti-Stokes luminescence at ~510 nm; as a result, a maximum temperature drop of 40 and 15 K has been demonstrated when the nanoribbons are pumped with a 514 or 532 nm laser. CdS is used as pigment in plastics, showing good thermal stability and weather fastness, chemical resistance and high opacity; as a pigment, CdS is known as cadmium yellow. About 2000 tons are produced annually as of 1982, representing about 25% of the cadmium processed commercially; the general commercial availability of cadmium sulfide from the 1840s led to its adoption by artists, notably Van Gogh and Matisse. The presence of cadmium in paints has been used to detect forgeries in paintings alleged to have been produced prior to the 19th century.
CdS and CdSe form solid solutions. Increasing amounts of cadmium selenide, gives pigments verging toward red, for example CI pigment orange 20 and CI pigment red 108; such solid solutions are components of photoresistors near infrared light. Cadmium sulfide is toxic when inhaled as dust, cadmium compounds general are classified as carcinogenic. Problems of biocompatibility have been reported. Cadmium sulphide information at Webelements IARC Monograph: "Cadmium and Cadmium Compounds" Last access November 2005. International Chemical Safety Card 0404 National Pollutant Inventory - Cadmium and compounds Repor
The Canon AL-1 was an FD mount, 35mm single-lens reflex camera introduced in March 1982. Its main feature was the "Quick Focus" focus-assist system, aimed at those who had trouble focusing through the viewfinder—either novices, or those with poor eyesight—and was intended to head off competition from the first full-autofocus cameras from other manufacturers, such as the Pentax ME F; as a lower-end camera, the AL-1 did not offer a long list of features. Instead, Canon focused on lowering price; the AL-1 provides focus-confirmation, aperture-priority autoexposure, a small selection of manual shutter speeds, including 10 second self-timer. It added a larger grip, the convenience of using of AAA cells for power; however the battery door is one of its weakness as most of the cameras that are found today on the market have their battery door broken or, changed. Its body was constructed from a special polycarbonate, painted to imitate metal. An ISO hotshoe, motor-drive connections, cable-release socket provide an acceptable level of compatibility with accessories.
It was the last SLR camera to carry Canon's 1960s-era logo on the pentaprism. The camera uses Canon's breech-lock FD mount, so users could choose from the wide variety of Canon FD lenses, as well as those from third parties. Users could utilise Canon R and FL lenses, but with some limitations. In 1987, Canon abandoned the FD mount in favour of the EF mount along with the EOS camera system, which uses the same concept as the T80 but with a new and incompatible mount designed around an all-electronic interface; the AL-1 marked Canon's first public foray into autofocus technology. While far from a true autofocus system, the camera acted a test for Canon engineers to evaluate phase detection for SLR cameras; the QF focus-assist system uses traditional phase detection linear CCD arrays in the base of the camera. Light is diverted to these sensors through a silvered mirror; when the light of the subject is in phase, the image is in focus. Below the viewfinder image, two red arrows indicate which direction to turn the focusing ring to achieve focus.
Optimum focus is indicated by a green light between the two arrows. Contrast detection is the system used for autofocus on most compact digital cameras in recent years. Due to the camera's lack of features, it was never overly popular and so it would be 1985 before Canon expanded on the concept though its competitors raced ahead. In 1983 Nikon introduced the F3AF, a special version of their pro-series F3, which used a special viewfinder with a built-in autofocus system connecting electronically to a motor in the lens. In 1985 Minolta introduced the Maxxum 7000, the world's first body-integrated autofocus SLR. Canon reacted to this with the T80, which integrated the focus system into the body and, as with the F3AF, connected electronically with a motor in the lens. YouTube video describing the function of the focusing element in the Canon AL-1 Canon AL-1 Quick Focus Information Page
The Canon T70 was a 35mm FD-mount single-lens reflex camera introduced in April 1984 as the second in Canon's T series. The T70 started with the concepts explored in 1983's T50, took them further, applied them to a more sophisticated camera. While the Program AE-only T50 was intended as a beginner's camera, the T70 gave the photographer a lot more control over the camera's operation while keeping the T-series philosophy of simplicity in control and operation intact. All film transport on the T70 was powered—loading and rewind; the continuous shooting rate, at 0.7 frames per second, was slower than rival motor drives, but the drive was nonetheless faster than most people could manually wind. To load the camera, the photographer had to pull the film leader out to an orange mark and close the back—the camera did the rest, loading the leader onto the spool, advancing to the first frame automatically. All powered camera functions drew on two AA batteries in the grip. A built-in lithium battery was used to store user settings.
The T70 used an LCD mounted on the top of the right-hand side of the camera as a major component of its user interface. Two buttons above the display labeled'UP' and'DOWN' adjusted the selected parameter and the results were shown on the LCD. Buttons on the left-hand top of the camera selected the parameter to be modified; the T70 included two different through-the-lens metering methods. Center-weighted average metering was the standard metering method, averaging over the whole frame with a slight preference towards the center of the frame, where the main subject is most to be. With backlit scenes, or ones where the subject is spotlit against a dark background, center-weighted averaging produces underexposure or overexposure, respectively. For such situations, the T70 supported selective area metering, which metered only the center 11% of the frame; the metering mode was selected by a sliding switch on the top left-hand side of the camera. This switch selected self-timer mode and had a Lock position.
The T70 supported eight different exposure modes. These were: Program AE. In this standard mode, the camera judges the shutter speed and aperture for average photographic scenes. Wide Program AE. Here, the camera is biased towards choosing narrow apertures for greater depth of field, most useful with wide-angle lenses. Tele Program AE. Here, the camera is biased towards choosing wider apertures for narrow depth of field and fast shutter speeds, most useful with telephoto lenses. Shutter-priority AE. Here, the user selects the camera chooses the correct aperture. Programmed flash AE; this is designed to work with the Speedlite 277T dedicated flash unit. Electronic flash AE. For flash exposures with non-dedicated flash units. Manual. Here, the photographer chooses both shutter speed. Stopped-down AE. For use with older FL-mount lenses that do not support open-aperture metering. For use with macro photography attachments such as extension tubes and bellows, for using non-Canon lenses with an adaptor. Cannot be selected with an FD lens attached.
A dedicated Command Back 70 supported date and data imprinting as well as time exposures, to take a photograph at a programmed time, to take time-lapse photos at programmed intervals. The shutter of the T70 was not battery dependent during bulb exposures, was one reason why the command back could support timed exposures of several hours duration; when it was introduced, the Canon T70 was considered technologically advanced compared to other SLR cameras. Reviewing the camera in Popular Science, Everett Ortner said that the T70 "could be...too good for amateurs. It is far removed from those other technological wonders designed for amateurs", he praised the high degree of control, coupled with automation, that the T70 allows photographers to use, reducing "the role of the camera from that of master to servant." Media related to Canon T70 at Wikimedia Commons Canon T70. From Canon's online Camera Museum. Photography in Malaysia. Canon T70 Camera. Retrieved on 20 October 2005
Canon FL lens mount
Canon FL refers to a lens mount standard for 35mm single-lens reflex cameras from Canon. It was introduced in April 1964 with the Canon FX camera; the FL mount was in turn replaced in 1971 by the Canon FD lens mount. FL lenses can be used on FD-mount cameras. Many mirrorless interchangeable-lens cameras are able to use Canon FL lenses via an adapter. Canon FX Canon FP Canon Pellix Canon FT QL Canon Pellix QL Canon TL Source:Canon released 3'levels' of standard lenses; the f/1.8 lenses were small and lightweight, f/1.4 were mid-range, the f/1.2 were professional level. The FL 19mm F3.5 was a true wide angle lens. Its rear projected far into the mirror box on an SLR, because of this, it could only be used on a camera with mirror lock-up, it could not be used on either Pellix model. The FL P 38mm F2.8 projected into the mirror box. It was specially designed for the Pellix and could not be used on any other camera because the moving mirror would hit the rear of the lens; this lens had a longer lens mount index, that only fit the deeper cutout at the top of the Pellix's lens mount, thus making it impossible to mount this lens on any other camera.
The FL M 100mm F4 was a special purpose bellows lens. It could only be used when mounted on a bellows, such as the Bellows FL, because it lacked a focusing ring; the list is complete. List of Canon products Canon Canon EOS Canon FD lens mount Single-lens reflex camera Digital single-lens reflex camera 135 film Canon FL
The Canon T60 was the last manual focus FD-mount 35 mm single-lens reflex camera sold by Canon. It was the final camera in Canon's T series, it was introduced as a cheap SLR system for export. It was never sold in Canon's home Japanese market. In some foreign markets, the higher price of the EOS cameras was a problem, while in others, there was demand for a cheap manual camera for photography students and the like; the T60 shared little with the other T-series models except for a superficial styling resemblance. Unlike them, it had only manual film loading and rewind. Film speed and shutter speed were set with traditional dials; the only auto-exposure mode supported was aperture priority AE. The camera would choose an appropriate shutter speed. Supported, of course, was full manual exposure, aided by the camera's built-in meter. Shutter speed range was 1/1000 second to 1 second, plus bulb. Canon did not manufacture the T60. Like a number of other low-end bodies sold by major camera companies, it was both built by Cosina, based upon Cosina's own CT-1 chassis.
Photography in Malaysia. The Canon T60. Retrieved on 20 October 2005. Canon T60 User Manual. Retrieved from the Canon FD Documentation Project on 20 October 2005