The 35 mm format, or 35 mm, is the common name for the 36×24 mm film format or image sensor format used in photography. It has an aspect ratio of 3:2, a diagonal measurement of 43 mm, it has been employed in countless photographic applications including single-lens reflex cameras, rangefinder cameras, mirrorless interchangeable-lens digital cameras, digital SLRs, point-and-shoot film cameras, disposable film cameras. The format originated with his introduction of the Leica camera in the 1920s, thus it is sometimes called the Leica Barnack format. The name 35 mm originates with the total width of the 135 film, the perforated cartridge film, the primary medium of the format prior to the invention of the full frame DSLR; the term 135 format remains in use. In digital photography, the format has come to be known as full frame, FF or FX, the latter invented as a trade mark of Nikon; the 35 mm format was sometimes called miniature format or small format, terms meant to distinguish it from medium format and large format.
The 35 mm format was conceived by Oskar Barnack by doubling the size of the 24×18 mm format used in cinema. The term 35 mm camera refers to a still photographic film camera which uses the 35 mm format on 135 film; such cameras have been produced by Leica, Argus, Canon, Olympus, Pentax, Carl Zeiss and numerous other companies. Some notable 35 mm camera systems are the original Leica, Leica M, Leica R, Nikon F, Argus C3, Canon FD, Canon EOS, Minolta OM, Pentax K-mount system, Minolta Maxxum/Dynax "A" mount system, the inter-compatible Contax and Yashica systems. Many digital image sensors approximate the dimensions of the 35 mm format, sometimes differing by fractions of a millimeter on one or both dimensions. Since 2007, Nikon has referred to their 35 mm format by the trade mark FX. Other makers of 35 mm format digital cameras, including Leica and Canon, refer to their 35 mm sensors as full frame. A true normal lens for 35 mm format would have a focal length of 43 mm, the diagonal measurement of the format.
However, lenses of 43 mm to 60 mm are considered normal lenses for the format, in mass production and popular use. Common focal lengths of lenses made for the format include 24, 28, 35, 50, 85, 105, 135 mm. Most a 50 mm lens is the one considered normal, any lens shorter than this is considered a wide angle lens and anything above is considered a telephoto lens. Wide angles shorter than 24 mm is called an extreme wide angle. Lenses above 50 mm but up to about 100 mm are called short telephoto or sometimes, as portrait telephotos, from 100 mm to about 200 mm are called medium telephotos, above 300 mm are called long telephotos. Many photographers think about angle of view in terms of 35 mm format lenses, due to the historic prevalence of the 35 mm format. For example, a photographer might associate a 50 mm focal length with a normal perspective, because a 50 mm lens produces that perspective on this format. With many smaller formats now common, lenses may be advertised or marked with their "35 mm equivalent" or "full-frame equivalent" focal length as a mnemonic.
This'equivalent' is computed by multiplying the true focal length of the lens by the ratio of the diagonal measurement of the native format to that of the 35 mm format. For example, a lens for APS-C format with a focal length of 40 mm, might be described as "60 mm." Although its true focal length remains 40 mm, its angle of view is equivalent to that of a 60 mm lens on a 35 mm format camera. Another example is the lens of the 2/3 inch format Fujifilm X10, marked with its true zoom range "7.1–28.4 mm" but has 35 mm-equivalent zoom control markings ranging from "28" to "112"
Single-lens reflex camera
A single-lens reflex camera is a camera that uses a mirror and prism system that permits the photographer to view through the lens and see what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be different from the final image; when the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured. Prior to the development of SLR, all cameras with viewfinders had two optical light paths: one path through the lens to the film, another path positioned above or to the side; because the viewfinder and the film lens cannot share the same optical path, the viewing lens is aimed to intersect with the film lens at a fixed point somewhere in front of the camera. This is not problematic for pictures taken at a middle or longer distance, but parallax causes framing errors in close-up shots. Moreover, focusing the lens of a fast reflex camera when it is opened to wider apertures is not easy.
Most SLR cameras permit upright and laterally correct viewing through use of a roof pentaprism situated in the optical path between the reflex mirror and viewfinder. Light, which comes both horizontally and vertically inverted after passing through the lens, is reflected upwards by the reflex mirror, into the pentaprism where it is reflected several times to correct the inversions caused by the lens, align the image with the viewfinder; when the shutter is released, the mirror moves out of the light path, the light shines directly onto the film. The Canon Pellix, along with several special purpose high speed cameras, were an exception to the moving mirror system, wherein the mirror was a fixed beamsplitting pellicle. Focus can be adjusted manually automatically by an autofocus system; the viewfinder can include a matte focusing screen located just above the mirror system to diffuse the light. This permits accurate viewing and focusing useful with interchangeable lenses. Up until the 1990s, SLR was the most advanced photographic preview system available, but the recent development and refinement of digital imaging technology with an on-camera live LCD preview screen has overshadowed SLR's popularity.
Nearly all inexpensive compact digital cameras now include an LCD preview screen allowing the photographer to see what the CCD is capturing. However, SLR is still popular in high-end and professional cameras because they are system cameras with interchangeable parts, allowing customization, they have far less shutter lag, allowing photographs to be timed more precisely. The pixel resolution, contrast ratio, refresh rate, color gamut of an LCD preview screen cannot compete with the clarity and shadow detail of a direct-viewed optical SLR viewfinder. Large format SLR cameras were first marketed with the introduction of C. R. Smith's Monocular Duplex. SLRs for smaller exposure formats were launched in the 1920s by several camera makers; the first 35mm SLR available to the mass market, Leica's PLOOT reflex housing along with a 200mm f4.5 lens paired to a 35mm rangefinder camera body, debuted in 1935. The Soviet Спорт a 24mm by 36mm image size, was prototyped in 1934 and went to market in 1937. K. Nüchterlein's Kine Exakta was the first integrated 35mm SLR to enter the market.
Additional Exakta models, all with waist-level finders, were produced up to and during World War II. Another ancestor of the modern SLR camera was the Swiss-made Alpa, innovative, influenced the Japanese cameras; the first eye-level SLR viewfinder was patented in Hungary on August 23, 1943 by Jenő Dulovits, who designed the first 35 mm camera with one, the Duflex, which used a system of mirrors to provide a laterally correct, upright image in the eye-level viewfinder. The Duflex, which went into serial production in 1948, was the world's first SLR with an instant-return mirror; the first commercially produced SLR that employed a roof pentaprism was the Italian Rectaflex A.1000, shown in full working condition on Milan fair April 1948 and produced from September the same year, thus being on the market one year before the east German Zeiss Ikon VEB Contax S, announced on May 20, 1949, produced from September. The Japanese adopted and further developed the SLR. In 1952, Asahi developed the Asahiflex and in 1954, the Asahiflex IIB.
In 1957, the Asahi Pentax combined the right-hand thumb wind lever. Nikon and Yashica introduced their first SLRs in 1959; as a small matter of history, the first 35 mm camera to feature through the lens light metering may have been Nikon, with a prototype rangefinder camera, the SPX. According to the website below, the camera used Nikon'S' type rangefinder lenses. Through-the-lens light metering is known as "behind-the-lens metering". In the SLR design scheme, there were various placements made for the metering cells, all of which used CdS photocells; the cells were either located in the pentaprism housing, where they metered light transmitted through the focusing screen. Pentax was the first manufacturer to show an early prototype 35 mm behind-the-lens metering SLR camera, named the Pentax Spotmatic; the camera was shown at the 1960 photokina show. However, the first
Micro Four Thirds system
The Micro Four Thirds system is a standard released by Olympus and Panasonic in 2008, for the design and development of mirrorless interchangeable lens digital cameras and lenses. Camera bodies are available from Blackmagic, DJI, JVC, Olympus, Sharp Corporation, Xiaomi. MFT lenses are produced by Cosina Voigtländer, DJI, Kodak, Olympus, Samyang, Sharp Corporation, Sigma, SLR Magic, Tokina and Xiaomi, amongst others. MFT shares the original image sensor size and specification with the Four Thirds system, designed for DSLRs. Unlike Four Thirds, the MFT system design specification does not provide space for a mirror box and a pentaprism, which facilitates smaller body and lens designs via the shorter flange focal distance of 19.25mm. The short flange distance, when combined with an adapter of proper depth, allows MFT bodies to use any lens made for a camera with a flange distance larger than 19.25mm. Still-camera lenses produced by Canon, Minolta, Nikon and Zeiss have all been adapted for MFT use - as well as lenses produced for cinema, e.g. PL mount or C mount.
For comparison of the original Four Thirds with competing DSLR system see Four Thirds system#Advantages and other considerations Compared to most digital compact cameras and many bridge cameras, MFT cameras have better, larger sensors, interchangeable lenses. They provide far greater control over depth-of-field than compact cameras. There are many lenses available. On top of this, a large number of other lenses can be fitted using an adapter. Different lenses yield greater creative possibilities. However, Micro Four Thirds cameras tend to be larger and more expensive than compact cameras. Compared to most digital SLRs, the Micro Four Thirds system is lighter. However, their sensors are smaller than full-frame or APS-C systems; as such, they may produce noisier/grainier images in low light conditions when compared with contemporary cameras with larger sensors. Unlike DSLRs, which use an optical viewfinder, Micro Four Thirds cameras use an electronic viewfinder. Resolutions and refresh speeds on these EVF displays were compared negatively to optical viewfinders, but today's EVF systems are faster and much higher resolution than the original displays.
Micro Four Thirds cameras always afford a greater depth-of-field than SLRs when shooting at the same focal length and aperture, but it is more difficult to design a wide-aperture lens for Micro Four Thirds. Original Micro Four Thirds cameras used a contrast-detection autofocus system, slower than the phase-detect autofocus, standard on DSLRs. To this day most Micro Four Thirds cameras continue to use a contrast-based focussing system. Although some current models, such as the Olympus OM-D E-M1 Mark II, feature a hybrid phase-detect/contrast detect system, Panasonic Lumix cameras have continued to use a contrast-based system called DFD. Both systems today provide focussing speeds to rival or surpass many current DSLRs; the image sensor of Four Thirds and MFT measures 18 mm × 13.5 mm, with an imaging area of 17.3 mm × 13.0 mm, comparable to the frame size of 110 film. Its area, ca. 220 mm², is 30% less than the quasi-APS-C sensors used in other manufacturers' DSLRs. The Four Thirds system uses a 4:3 image aspect ratio, like compact digital cameras.
In comparison, DSLRs adhere to the 3:2 aspect ratio of the traditional 35 mm format. Thus, "Four Thirds" refers to the aspect ratio of the sensor. However, the chip diagonal is shorter than 4/3 of an inch; the MFT design standard specifies multiple aspect ratios: 4:3, 3:2, 16:9, 1:1. With the exception of two MFT cameras, all MFT cameras record in a native 4:3 format image aspect ratio, through cropping of the 4:3 image, can record in 16:9, 3:2 and 1:1 formats. In addition, all current Micro Four Thirds cameras have sensor dust removal technologies; the MFT system design specifies a bayonet type lens mount with a flange focal distance of 19.25 mm. By avoiding internal mirrors, the MFT standard allows a much thinner camera body. Viewing is achieved on all models by live view electronic displays with LCD screens. In addition, some models feature a built-in electronic viewfinder, while others may offer optional detachable electronic viewfinders. An independent optical viewfinder matched to a particular non-zoom prime lens is sometimes an option.
The flange diameter is about 38 mm, 6 mm less than that of the Four Thirds system. Electrically, MFT uses an 11-contact connector between lens and camera, adding to the nine contacts in the Four Thirds system design specification. Olympus claims full backward compatibility for many of its existing Four Thirds lenses on MFT bodies, using a purpose built adapter with both mechanical and electrical interfaces; the shallow but wide MFT lens mount allows the use of existing lenses including Leica M, Leica R, Olympus OM system lenses, via Panasonic and Olympus adapters. Aftermarket adapters include Leica Screw Mount, Contax G, C mount, Arri PL mount, Canon and Pentax, amongst others. In fact any still camera, movie or video camera interchangeable lens that has a flange focal distance greater than or marginally less than 20 mm can be used on MFT bodies vi
The Olympus OM-3 is a manual camera without automatic exposure modes, an mechanical shutter. Introduced in 1983, the OM-3 was the first of a new series of professional camera bodies designed to update the OM-1 and OM-2; these new bodies, which continued with the more popular OM-4, included a number of refinements over their predecessors. The most significant changes made were to the metering system; the OM-3 and OM-4 featured multi-spot metering in addition to the centre-weighted metering on the earlier bodies. This allowed the user to take a number of spot meter readings, all of which were used by the camera to calculate the correct exposure; the system featured "highlight" and "shadow" buttons which allowed the photographer to identify parts of a scene that should be exposed as white or black respectively. The metering system used a liquid crystal display in place of the older match needle design of the OM-1 and OM-2. Other refinements were present, including a faster maximum shutter speed of 1/2000 second and a built in flash hot shoe.
The OM-3 sold in smaller quantities than its electronic sister, the OM-4. This may be because the OM-1n remained in production and offered an alternative mechanical body for the OM system at a fraction of the price, albeit with less sophisticated metering. After a short production run, the OM-3 was discontinued in 1986; as a result, OM-3 bodies today are much rarer than OM-4s, those in good condition are sought after by collectors. Media related to Olympus OM-3 at Wikimedia Commons Olympus OM3 A user review of the Olympus OM-3
Olympus Corporation is a Japanese manufacturer of optics and reprography products. Olympus was established on 12 October 1919 specializing in microscopes and thermometers. Olympus holds a 70-percent share of the global endoscope market, estimated to be worth US$2.5 billion. Its global headquarters are located in Shinjuku, Japan. In 1936, Olympus introduced its first camera, the Semi-Olympus I, fitted with the first Zuiko-branded lens; the first innovative camera series from Olympus was the Pen, launched in 1959. The half-frame format, allowing 72 pictures of 18 × 24mm format on a standard 36 exposure roll of film, made Pen cameras compact and portable for their time; the Pen system design team, led by Yoshihisa Maitani created the OM system, a full-frame professional 35mm SLR system designed to compete with Nikon and Canon's bestsellers. The OM system introduced a new trend towards more compact cameras and lenses, being much smaller than its competitors and presenting innovative design features such as off-the-film metering and OTF flash automation.
The system included 14 different bodies 60 Zuiko-branded lenses, numerous camera accessories. In 1983, along with Canon, branded a range of video recording equipment manufactured by JVC, called it "Olympus Video Photography" employing renowned photographer Terance Donovan to promote the range. A second version of the system was available the year after, but this was Olympus' last foray into the world of consumer video equipment until digital cameras became popular. Tsuyoshi Kikukawa, to become President of Olympus, foresaw the demand for the digital SLR, is credited with the company's strategy in digital photography, he fought for commitment by Olympus to enter the market in high-resolution photographic products. As a result of his efforts, Olympus released an 810,000-pixel digital camera for the mass market in 1996, when the resolution of rivals' offerings were less than half; the next year, Olympus hit the market with a 1.41 million pixel camera. By 2001, the company's annual turnover from digital photography was in excess of ¥100 billion.
Olympus manufactures compact digital cameras and is the designer of the Four-Thirds System standard for digital single-lens reflex cameras. Olympus' Four Thirds system flagship DSLR camera is the E-5 released in 2010. Olympus is the largest manufacturer of Four-Thirds lenses, under the Zuiko Digital brand. At one time, Olympus cameras used only the proprietary xD-Picture Card for storage media; this storage solution is less popular than more common formats, recent cameras can use SD and CompactFlash cards. The most recent development is Olympus' focus on the Micro Four Thirds system. Olympus first introduced the Microcassette; the Olympus Pearlcorder L400, released in the 1980s, was the smallest and lightest Microcassette Voice recorder offered for sale, 2.9 × 0.8 × 2.0 in. / 73 × 20 × 52 3.2 oz. In 2012, the company announced that Sony and Fujifilm had offered forming a capital alliance and the company would focus on Mirrorless interchangeable-lens cameras. Olympus manufactures endoscopic, electrocautery and cleaning and disinfection equipment.
The first flexible Endoscope in the world was manufactured by Olympus in Tokyo. Through its comprehensive product range and its reactivity to market innovations, Olympus enjoys a virtual stranglehold of the world market in gastro-intestinal endoscopes, it has 70% share of the global market whose estimated valued at US$2.5 billion. On 28 September 2012, Olympus and Sony announced that the two companies will establish a joint venture to develop new surgical endoscopes with 4K resolution and 3D capability. Since the beginning, the company has been a manufacturer of microscopes and optics for specialised needs, such as medical use; the first microscope manufactured at Olympus was called the Asahi. Olympus is a worldwide renowned manufacturer of microscopes. Olympus offers a complete range of microscopes, which covers applications from education and routine studies up to state of the art research imaging systems, both in life science and materials science. Olympus Scientific Solutions Americas Corporation is a Waltham, Massachusetts-based manufacturer, is a subsidiary of Olympus Corporation.
One of its companies, for example, is Olympus Imaging and Measuring Systems, specializing in imaging instruments for testing and measurement during industrial inspections. Olympus manufactures and sells industrial scanners, flaw detectors and transducers, thickness gages, digital cameras, image analysis software, industrial videoscopes, light sources, XRF and XRD analyzers, high-speed video cameras. 1919: The company was founded as Takachiho Seisakusho. In Japanese mythology, deities live on the peak of Mt. Takachiho; the first corporate logo was TOKIWA, derived from Tokiwa Shokai, the company that the founder, Takeshi Yamashita, had worked for. Tokiwa Shokai held an equity stake in Takachiho Seisakusho and was responsible for marketing Takachiho products; the logo reads "TOKIWA TOKYO". The "G" and "M" marks above are believed to be the initials of Goro Matsukata, the president of Tokiwa Shokai. 1921: The Olympus brand was introduced in February 1921. This logo was used for other products. Brochures and newspaper ads for cameras used this logo.
The OLYMPUS TOKYO logo is still in use today. There was a period. OIC stood for Optical Industrial Company, a translation of Olympus' Japanese corporate name at that time; this logo was used for the GT-I and GT-II endoscopes, a
A lens mount is an interface – mechanical and also electrical – between a photographic camera body and a lens. It is confined to cameras where the body allows interchangeable lenses, most the rangefinder camera, single lens reflex type or any movie camera of 16 mm or higher gauge. Lens mounts are used to connect optical components in instrumentation that may not involve a camera, such as the modular components used in optical laboratory prototyping which join via C-mount or T-mount elements. A lens mount may be a bayonet-type, or a breech-lock type. Modern still camera lens mounts are of the bayonet type, because the bayonet mechanism aligns mechanical and electrical features between lens and body. Screw-threaded mounts are fragile and do not align the lens in a reliable rotational position, yet types such as the C-mount interface are still in use for other applications like video cameras and optical instrumentation. Bayonet mounts have a number of tabs around the base of the lens, which fit into appropriately sized recesses in the lens mounting plate on the front of the camera.
The tabs are "keyed" in some way to ensure that the lens is only inserted in one orientation by making one tab a different size. Once inserted the lens is fastened by turning it a small amount, it is locked in place by a spring-loaded pin, which can be operated to remove the lens. Lens mounts of competing manufacturers are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance from the lens mount to the film or sensor can be different. Many allege that these incompatibilities are due to the desire of manufacturers to "lock in" consumers to their brand. In movie cameras, the two most popular mounts in current usage on professional digital cinematography cameras are Arri's PL-mount and Panavision's PV-mount; the PL-Mount is used both on Arri and RED digital cinematography cameras, which as of 2012 are the most used cameras for films shot in digital. The Panavision mounts are used with Panavision lenses, thus are only available on Panaflex cameras or third-party cameras "Panavised" by a Panavision rental house, whereas the PL-mount style is favored with most other cameras and cine lens manufacturers.
Both of these mounts are held in place with locating pins and friction locking rings. Other mounts which are now historical or a minority in relation to current practices are listed below. For small camera modules, used in e.g. CCTV systems and machine vision, a range of metric thread mounts exists; the smallest ones can be found in e.g. cellphones and endoscopes. The most common by far is the M12x0.5, followed by M8x0.5 and M10x0.5. M4.2x0.2 M4.6x0.25 M5x0.35 M5.5x0.35 M6x0.35 M6.4x0.25 M7x0.35 M8x0.35 M8x0.5 M9x0.5 M10x0.5 M12x0.5 The axial adjustment range for focusing Ultra wide angle lenses and some Wide-angle lenses in large format cameras is very small. So some manufacturers offered special focusing lens mounts, so-called wide-angle focusing accessories for their cameras. With such a device, the lens could be focused without moving the entire front standard. Secondary lens refers to a multi-element lens mounted either in front of a camera's primary lens, or in between the camera body and the primary lens.
SLR camera & interchangeable-lens manufacturers offer lens accessories like extension tubes and secondary lenses like teleconverters, which mount in between the camera body and the primary lens, both using and providing a primary lens mount. Various lensmakers offer optical accessories that mount in front of the lens. Canon PowerShot A and Canon PowerShot G cameras have a built-in or non-interchangeable primary lens, Canon has "conversion tube" accessories available for some Canon PowerShot camera models which provide either a 52mm or 58mm "accessory/filter" screw thread. Canon's close-up, wide-, tele-conversion lenses have 2, 3, 4-element lenses so they are multi-element lenses and not diopter "filters". Lens mount. A lens can be adapted to a camera body with a smaller flange focal distance by adding space between the camera and the lens; when attempting to adapt a lens to a camera body with a larger flange focal distance, the adapter must include a secondary lens in order to compensate. This has the side effect of decreasing the amount of light that reaches the sensor, as well as adding a crop factor to the lens.
Without the secondary lens, these adapters will function as an extension tube and will not be able to focus to infinity. ISO metric screw thread Lens board ^ A: The authoritative normative source for 4/3 standards information is Four-Thirds. Org and not 3rd-party reviews.4/3's published facts: "Size of the 4/3-type Sensor: The standard diagonal length of the sensor is 21.63 millimetres. It is half that of 35-mm film format The image circle of the interchangeable lens is specified based on this diagonal length. Th
Four Thirds system
The Four Thirds System is a standard created by Olympus and Eastman Kodak for digital single-lens reflex camera and mirrorless camera design and development. The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different manufacturers. U. S. Patent 6,910,814 seems to cover the standard. Proponents describe it as an open standard, but companies may only use it under a non-disclosure agreement. Unlike older single-lens reflex systems, Four Thirds was designed from the start to be digital. Many lenses are extensively computerised, to the point that Olympus offers firmware updates for many of them. Lens design has been tailored to the requirements of digital sensors, most notably through telecentric designs; the size of the sensor is smaller than for most DSLRs and this implies that lenses telephoto lenses, can be smaller. For example, a Four Thirds lens with a 300 mm focal length would cover about the same angle of view as a 600 mm focal length lens for the 35 mm film standard, is correspondingly more compact.
Thus, the Four Thirds System has crop factor of about 2, while this enables longer focal length for greater magnification, it does not aid the manufacture of wide angle lenses. The image sensor format, between those of larger SLRs and smaller point-and-shoot compact digital cameras, yields intermediate levels of cost and convenience; the name of the system stems from the size of the image sensor used in the cameras, referred to as a 4/3" type or 4/3 type sensor. The common inch-based sizing system is derived from vacuum image-sensing video camera tubes, which are now obsolete; the imaging area of a Four Thirds sensor is equal to that of a video camera tube of 4/3 inch diameter. The usual size of the sensor is 18 mm × 13.5 mm, with an imaging area of 17.3 mm × 13.0 mm. The sensor's area is about 30–40% smaller than APS-C sensors used in most other DSLRs, but still around 9 times larger than the 1/2.5" sensors used in compact digital cameras. Incidentally, the imaging area of a Four Thirds sensor is identical to that of 110 film.
The emphasis on the 4:3 image aspect ratio sets Four Thirds apart from other DSLR systems, which adhere to the 3:2 aspect ratio of the traditional 35mm format. However, the standard only specifies the sensor diagonal, thus Four Thirds cameras using the standard 3:2 aspect ratio would be possible. For instance, the Panasonic GH1 uses a multi-aspect sensor designed to maximize use of the image circle at 4:3, 3:2, 16:9. Sensor aspect ratio influences lens design. For example, many lenses designed by Olympus for the Four Thirds System contain internal rectangular baffles or permanently mounted "petal" lens hoods that optimise their operation for the 4:3 aspect ratio. In an interview John Knaur, a Senior Product Manager at Olympus, stated that "The FourThirds refers to both the size of the imager and the aspect ratio of the sensor", he pointed out the similarities between 4:3 and the standard printing size of 8×10 as well as medium format 6×4.5 and 6×7 cameras, thus helping explain Olympus' rationale on choosing 4:3 rather than 3:2.
The smaller sensor size makes possible smaller and lighter camera lenses. In particular, the Four-Thirds system allows the development of large aperture lenses. Corresponding lenses become larger and more expensive when designed for larger sensor formats. Telecentric optical path means that light hitting the sensor is traveling closer to perpendicular to the sensor, resulting in brighter corners, improved off-center resolution on wide angle lenses; because the flange focal distance is shorter than those on Canon FD, Canon EF, Nikon F and Pentax K, lenses for many other SLR types including the old Olympus OM System can be fitted to Four Thirds cameras with simple mechanical adapter rings. Such mechanical adapter rings require manual setting of focus and aperture. A series of tests provides a demonstration; the main disadvantage of a smaller sensor, with a pixel count that matches a larger sensor, is the reduction in incoming light hitting the light sensitive part of each pixel of the sensor. This is true if the Four Thirds camera and lens are properly designed to focus all captured light onto the smaller light circle circumscribing the smaller sensor.
The reason is that a smaller pixel has a proportionately smaller light sensitive area because the pixel loses a larger proportion of its total area to secondary circuitry and edge shading than a larger pixel. With less captured light to work with each pixel output voltage requires additional amplification with associated higher signal noise, resulting in increased chromatic and color noise as well as reduced dynamic range. A telecentric lens design helps reduce this problem but still leaves a smaller sensor, with smaller pixels, more sensitive to the angle of incoming light, among other things producing a more pronounced image corner light fall off; the resolution of a sensor is measured as the total sensor pixel count in Mega Pixels or MP. From an image resolution point of view, a large sensor consisting of small sensor pixels is therefore desirable; the resolution of a lens is defined as the ability to produce an image of, for example, 100 black and white line pairs per millimeter. This corresponds to a line pair distance of 10 µm.
Since this is in the neighborhood of how small pixels can be manufactured today, this