page_title: Canon EOS
section_title: EOS flash system
hierarchical_section_title: Canon EOS / EOS flash system
caption_attribution_description: English: A Canon Speedlite 550EX flash unit.
context_page_description: Canon EOS is an autofocus single-lens reflex camera and mirrorless camera series produced by Canon Inc. Introduced in 1987 with the Canon EOS 650, all EOS cameras used 35 mm film until October 1996 when the EOS IX was released using the new and short-lived APS film. In 2000, the D30 was announced, as the first digital SLR designed and produced entirely by Canon. Since 2005, all newly announced EOS cameras have used digital image sensors rather than film. The EOS line is still in production as Canon's current digital SLR range, and, with the 2012 introduction of the Canon EOS M, Canon's mirrorless interchangeable-lens camera system. In 2018 the system was further extended with the introduction of the EOS R camera, Canon's first full frame mirrorless interchangeable lens system.
  The development project was called "EOS". EOS is also the name of the goddess of dawn in Greek mythology, which further signifies the design's generational stature.
  The EOS emblem was created using Handel Gothic typography.
  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.
context_section_description: 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. Later models, including RT in their model name, can also communicate via radio links, where up to 16 units can make up a network. 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.
caption: A Speedlite 550EX, an early E-TTL flash from 1998
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