Compatibility: This lens is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L, and EF 100-400/4.5-5.6L.
Shutter Type: Programmed electronic shutter1/2 to 1/250 sec. Slow synchro for low light
Flash Mode: Constant firing flash (automatic light adjustment), recycle time: 6.5 seconds or less (when using new batteries), effective flash range: 0.3 to 2.7m