page_title: Canon EOS flash system
section_title: 550 EX
hierarchical_section_title: Canon EOS flash system / Speedlite products / 500 and 600 series flashes / 550 EX
caption_attribution_description: English: A Canon Speedlite 550EX flash unit.
context_page_description: Canon's EOS flash system refers to the photographic flash mechanism used on Canon's film or digital EOS single-lens reflex cameras. The line was first introduced in 1987. It has gone through a number of revisions over the years, as new flash exposure metering systems have been introduced. The main light-metering technologies are known as A-TTL, E-TTL, and E-TTL II.
  The EOS flash system is capable of wireless multiple flash control, whereby a master flash unit IR or RF transmitter mounted on the camera body can control up to 3 or 5 groups of flash units. The Canon EOS 7D is the first Canon body to be able to control Speedlites wirelessly without the use of a Master Speedlite or IR transmitter; four other EOS models, the 60D, 600D, 650D, 70D, and 700D, also have wireless flash capabilities. The 7D is capable of handling three slave groups. The other cameras can handle two slave groups.
context_section_description: The Speedlite 550EX (introduced September 1998) is a flash made by Canon for use with their EOS line of cameras, primarily the Canon EOS 3. The 550 EX can act as a controller that enables wireless control of other flashes. Until the release of the Speedlite 580EX in late 2004, the 550EX was Canon's top-of-the-line flash.
caption: A Canon Speedlite 550EX flash unit
exif: {"Image Make": "Canon", "Image Model": "Canon EOS 5D Mark II", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS4 Windows", "Image DateTime": "2016:05:14 14:27:40", "Image Artist": "Ashley Pomeroy", "Image ExifOffset": "240", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "718", "Thumbnail JPEGInterchangeFormatLength": "0", "EXIF ExposureTime": "1", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2016:05:14 13:18:55", "EXIF DateTimeDigitized": "2016:05:14 13:18:55", "EXIF ShutterSpeedValue": "0", "EXIF ExposureBiasValue": "1", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "50", "EXIF SubSecTime": "56", "EXIF SubSecTimeOriginal": "56", "EXIF SubSecTimeDigitized": "56", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "3000", "EXIF ExifImageLength": "2145", "EXIF FocalPlaneXResolution": "5616000/1459", "EXIF FocalPlaneYResolution": "1872000/479", "EXIF FocalPlaneResolutionUnit": "2", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard"}