|This article relies on references to primary sources. (April 2008)|
The Canon EOS (Electro-Optical System) autofocus 35 mm film and digital SLR camera system was introduced in 1987 with the Canon EOS 650 and is still in production as Canon's current DSLR and recently released Canon EOS M mirrorless interchangeable-lens camera (MILC) systems. The acronym "EOS" was chosen for Eos, the Titan Goddess of dawn in Greek mythology, and is often pronounced as a word (UK // or US //), although some spell out the letters, reading it as an initialism.
It competes primarily with the Nikon F series and its successors, as well as autofocus SLR systems from Olympus Corporation, Pentax, Sony/Minolta, and Panasonic/Leica. In 2010, Canon held 44.5% market share in DSLRs.
EF lens mount 
The bayonet-style EF lens mount is at the centre of the EOS camera system. Breaking compatibility with the earlier FD mount, it was designed with no mechanical linkages between moving parts in the lens and in the camera. The aperture and focus are controlled via electrical contacts, with motors in the lens itself. This was similar in some ways to Canon's earlier attempt at AF with the T80 and Nikon's 1983 F3AF (and to many of Nikon's more recent autofocus lenses), and other manufacturers including Contax (with its G series of interchangeable-lens 35 mm rangefinder cameras) and Olympus (with its Four Thirds System) have since embraced this type of direct drive system. It is a large lens mount compared to most of its competition, enabling the use of larger aperture lenses.
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EOS flash system 
The flash system in the EOS cameras has gone through a number of evolutions since its first implementation. The basic EOS flash system was actually developed not for the first EOS camera, but rather for the last high-end FD-mount manual-focus camera, the T90, launched in 1986. This was the first Canon camera with through-the-lens (TTL) flash metering, although other brands had been metering that way for some time. It also introduced the A-TTL (Advanced TTL) system for better flash exposure in program mode, using infrared preflashes to gauge subject distance.
This system was carried over into the early EOS cameras wholesale. A-TTL largely fell out of favor, and was replaced by E-TTL (Evaluative TTL). This used a pre-flash for advanced metering, and used the autofocus system to judge where the main subject was for more accurate exposure. E-TTL II, which was an enhancement in the camera's firmware only, replaced E-TTL from 2004.
Canon Speedlite-brand flashes have evolved alongside the cameras. They are capable of wired and wireless multi-flash setups, the latter using visible or infrared pulses to synchronise. Canon also produces Speedlite accessories, including the OC-E3 Off-Camera Shoe Cord which can be used to hand-hold the flash while allowing the camera to control it through the cord. The Off-Camera Shoe Cord is popular among portrait photographers who need to have more control over lighting than a camera mounted flash can offer.
EOS cameras 
As of 2007, Canon has released no fewer than 40 EOS SLR camera models, starting with the introduction of the EOS 650 in 1987. In the 1990s, Canon worked with Kodak to produce digital camera bodies, starting with the EOS DCS 3 in 1995. The first digital EOS SLR camera wholly designed and manufactured by Canon is the EOS D30, released in 2000.
Canon also sold a manual-focus camera, the Canon EF-M, which uses the same EF lens mount as the EOS cameras. It comes with all the automatic and manual exposure functions but lacks autofocus. However, it comes equipped with a split-screen/microprism focusing screen for precise manual focusing.
Eye-controlled focusing 
Through the tracking of eyeball movements, EOS cameras equipped with eye-controlled focusing (ECF) are able to choose the appropriate autofocus point based on where the user is looking in the viewfinder frame. ECF comes especially useful in sports photography where the subject may shift its position in the frame rapidly.
Canon has not continued its use of eye-controlled focusing with its digital SLRs, however. The EOS Elan 7NE is the last EOS camera to have this function.
Quick control dial 
Most prosumer and professional level EOS cameras feature a large quick control dial (QCD) on the camera back. Allowing easy operation of the camera using the thumb, the QCD is used for quick access to often-used functions that may otherwise require a more complicated procedure of button-presses and dial-clicks.
Cameras equipped with the QCD can easily be operated with one hand (forefinger on the main dial, thumb on the QCD) without taking the eye off the viewfinder.
Some useful functions that a QCD is programmed to do include setting exposure compensation, setting of aperture in manual exposure mode and scrolling of images and menus in digital EOS cameras.
Multi-point autofocus system 
Currently, top-line EOS cameras have 61 autofocus (AF) points, the most in their class. Two Canon cameras have this system—the EOS 5D Mark III, on sale since March 2012, and the EOS-1D X, announced in October 2011 and originally scheduled for sale in April 2012, but delayed until June 2012. The release of the 5D MkIII gave Canon the lead once again in this category; previously, its top-line cameras had 45 AF points, which led the industry until Nikon released its D3 and D300 DSLRs with 51-point AF systems.
A higher number of AF points increases the chances of a sharply-focused photograph in situations where the subject travels across the frame at high speeds (e.g., sports, birds). The number, type, features and performance of autofocus point array systems is likely to continue to evolve.
Having so many AF points also helps relieve the photographer from having to use the 'lock focus and recompose' method of framing a photograph, since the subject will most probably have been picked up by one or more of the AF points. Even though the camera is intelligent enough to select the correct AF point(s) most of the time, EOS cameras equipped with a multi-point AF system will still allow the photographer to manually select an AF point.
The EOS-3, EOS-1v, and all EOS-1D models prior to the EOS-1D X feature a 45-point AF system. Almost all Canon DSLRs introduced since late 2005, starting from the EOS 20D and the Rebel XTi (400D), feature a nine-point AF system in a diamond-shape formation. The EOS 5D, released in 2005, takes this 9-point AF system a step further by introducing six more 'invisible' AF points (i.e. not user-selectable) in helping the camera acquire focus faster during subject tracking. There are five exceptions to Canon's recent rule of a 9-point AF system. The EOS 1000D (Rebel XS) has the 7-point AF system of most older Canon DSLRs. The EOS 7D, released in 2009, has a 19-point AF layout, fitting essentially within the same diamond-shaped area of the frame as the nine-point layout. The EOS 5D Mark III, released in March 2012, and the EOS-1D X, released in June 2012, have 61-point AF layouts. The EOS 6D, announced in September 2012, has an 11-point layout.
For the earlier generation of 45-point AF system, the central column of 1 or 2 sensors (7 in all up to EOS-1Ds Mk II, EOS-1D Mk II N) are cross-type sensors, which are sensitive to both vertical and horizontal lines to offer a high degree of accuracy. The EOS-1Ds Mk III, replaced by the EOS-1D X, has 19 cross-type sensors for higher accuracy, as well as placing the cross-type sensors to complement the Rule of Thirds. The other Canon professional SLR replaced by the EOS-1D X, the APS-H EOS-1D Mk IV, has 39 cross-type sensors, a major increase from the 19 of the Mk III. Of the 61 AF points of the EOS-1D X and 5D MkIII, 21 central points and 20 outer points are cross-type, and five central points are dual-cross-type (sensitive to diagonal lines in addition to horizontal and vertical).
Similarly, all nine AF points on later generations of the X0D series (beginning with the 40D and continuing through the current 60D) are cross-type sensors for higher accuracy, and the center sensor is dual-cross-type for even greater accuracy and sensitivity. In June 2012, the EOS 650D (Rebel T4i) became the first consumer-level Canon to receive this AF system.
Naming scheme 
Identical Canon models are sometimes marketed under different names in different parts of the world. For example, the EOS Rebel 2000 known in the Americas is also known as EOS Kiss III in Japan, and EOS 300 in other parts of the world.
|Target Market Segment||Typically Common Features||International||Americas||Japan|
|Entry-level/consumer||Pentamirror viewfinder, lighter and cheaper (plastic) build than other ranges, APS-C sized sensor on digital models. Built-in small pop-up flash unit. Single CF card slot on three-digit models starting with the 300D through the 400D (which predate the 4-digit series and the subcompact 100D); single SD slot on all models since.||3- or 4-digit model number.
E.g., EOS 650D, EOS 300X, EOS 1100D, EOS 100D
|Rebel (used in North America since 1990)
E.g., EOS Digital Rebel T3, EOS Rebel T4i, EOS Rebel SL1
|Kiss (used in Japan since 1993)
E.g., EOS Kiss Digital N, EOS Kiss X6i, EOS Kiss X7
|Advanced amateur/midrange||Pentaprism viewfinder, higher frame rate and more rugged (typically magnesium alloy) construction than contemporary "entry-level" models. Partial weather sealing and crop APS-C sized sensor on digital models. Built-in small pop-up flash unit. Single CF card slot on digital models through the 50D; single SD slot on the 60D.||2-digit model number
E.g., EOS 33V, EOS 40D.
E.g., EOS Elan 7N (DSLRs share the same naming scheme as International)
E.g., EOS 7s
|Prosumer/high-end||Full frame sensor (APS-C for 7D), somewhat better weather sealing than the amateur enthusiast line, and tougher construction. No built-in flash unit (except EOS 5 and 7D). Single CF card slot on digital models except for the 5D Mk III, with two slots (one CF and one SD), and the 6D, with one SD slot.||1-digit model number
With the introduction of the EOS 7D in 2009 the 1-digit (xD) formerly reserved for full-frame cameras is now also used to designate the continuation of the crop-sensor (APS-C) premium consumer line. Having been released for three years, there is currently no direct replacement to the 7D line (e.g., 7D Mark II). Instead, the company's cheapest and most versatile full frame camera to date, the EOS 6D, was announced in September 2012.
E.g., EOS 7D.
|Same as International, except EOS A2 (EOS 5)||Same as International|
|Professional/flagship||More rugged build and better weathersealing than premium models, larger build with vertical grip, 100% viewfinder field of view, faster performance. APS-H sized sensors on 1D models through the Mark IV and 35mm "Full-frame digital SLR" sensors on 1Ds models; the newest 1-series body, the Canon EOS-1D X, is full-frame. Single CF slot on the original 1D and 1Ds; dual card slots for redundancy/backup on all other models (CF + SD on models prior to the 1D X, dual CF on 1D X).||Model number 1||Same as International||Same as International|
Film cameras 
This is a list of the 35 mm Film and APS Canon EOS models in order of introduction:
Digital cameras 
Prior to the introduction of the EOS D30 digital SLR, Kodak produced four digital SLRs also sold under the Canon brand. These cameras used a digital camera back with the image sensor and associated electronics designed and built by Kodak together with modified internals of the EOS-1N film SLR. Due to the used Canon EOS body these four digital SLRs can accept EF lenses. The four cameras were:
|EOS DCS3||July 1995|
|EOS DCS1||December 1995|
|EOS D2000/Kodak DCS520||March 1998|
|EOS D6000/Kodak DCS560||December 1998|
After termination of the agreement by Canon, Kodak cooperated with Sigma – who at that time had a Canon license – to produce the Kodak DCS Pro SLR/c based on a SA9 SLR body in 2004, which was compatible with EF lenses.
The following digital SLRs, starting from the D30, had bodies and sensors completely designed and manufactured by Canon (except for the Canon EOS-1D, which uses a Panasonic sourced CCD sensor).
See also 
- Canon Corporation
- Comparison of Canon EOS digital cameras
- Canon Cinema EOS
- Canon FD lens mount
- Canon FL
- Canon EF lens mount
- List of Canon products
- Canon EF-S lens mount, a derivative of the EF mount designed for DSLRs with APS-C sensors
- Canon EF-M lens mount, a derivative of the EF mount designed for MILCs with APS-C sensors
Single lens reflex 
- "DSLR Worldwide Market Share, 2010". Retrieved 2 May 2011.
- "Canon History Hall: Birth of New-Generation Autofocus SLR Camera, "EOS"". Retrieved 29 January 2010.
- "Canon U.S.A. Announces the Highly Anticipated EOS 5D Mark III Digital SLR Camera" (Press release). Canon U.S.A. 2 March 2012. Retrieved 12 April 2012.
- "Canon U.S.A. Introduces The New Canon EOS-1D X Digital SLR Camera, Re-Designed From The Inside Out" (Press release). Canon U.S.A. 18 October 2011. Retrieved 18 October 2011.
- Carnathan, Bryan (12 April 2012). "Canon Announces Delay of EOS 1D X and EF 24-70mm f/2.8 L II USM Lens". The-Digital-Picture.com. Retrieved 12 April 2012.
- "Canon 1D Mark IV". Usa.canon.com. 25 May 2006. Retrieved 30 December 2010.
- "CANON U.S.A.'S NEW EOS REBEL XSi PLACES SUPERIOR OPTICS AND PROFESSIONAL FEATURES INTO THE HANDS OF EMERGING PHOTO ENTHUSIASTS". Retrieved 25 February 2008. "Canon U.S.A., Inc.'s EOS Rebel series of digital single lens reflex cameras – the cameras that defined and refined what it means to be an "entry level" digital SLR"
- "EOS 450D: get ready to play". Archived from the original on 29 January 2008. Retrieved 25 February 2008. "the model presents consumers with an unprecedented level of image quality"
- "Canon EOS 40D brings new EOS platform to advanced amateur market". Archived from the original on 12 November 2007. Retrieved 25 February 2008. "Canon today introduces its latest digital SLR for advanced amateurs and semi-professionals"
- "The Wait is Over: CANON U.S.A.'S HIGHLY ANTICIPATED EOS 40D DIGITAL SLR DELIVERS HIGH-RESOLUTION IMAGE QUALITY, HIGH-SPEED SHOOTING AND HIGH-END FUNCTIONALITY". Retrieved 25 February 2008. "Building on the success of Canon's perennially popular "prosumer" EOS 20D and 30D models, the EOS 40D advances the state-of-the-art for mid-range Digital SLR cameras"
- "NEW CANON EOS 5D IS A PREMIUM DIGITAL SLR AT AN AFFORDABLE PRICE OFFERING A FULL-FRAME SENSOR WITH 12.8 MEGAPIXELS OF RESOLUTION". Retrieved 25 February 2008. "The New Canon EOS 5D Camera Is a Premium DSLR for Under $3,300"
- "CANON U.S.A.'s NEW LINE-LEADING, 21.1-MEGAPIXEL, FULL-FRAME EOS-1Ds MARK III DIGITAL SLR KEEPS CANON AT THE TOP OF THE PRO PHOTO CLASS". Retrieved 25 February 2008. "While Canon's EOS-1D series has dominated the 35mm-based professional Digital SLR market for the past six years"
- Canon EOS Gamma Curves at Light Illusion
- EOS Camera Systems homepage at Canon.com
- EF lens specification chart (pdf)
- The Canon EOS FAQs
- Canon EOS Technoclopedia – an extensive system overview for Canon EOS incl. 3rd party manufacturers
- Flash Photography with Canon EOS Cameras – Part 1 – Part 2 – Part 3
- Canon Camera Museum
|Canon EOS Film SLR timeline|
|Canon EOS Digital SLR timeline (comparison)|
Specialty models: C - Cinema EOS | a - Astrophotography
Naming of Entry Level models: Rebel - Americas | Kiss - Japan