Canon EF lenses
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| "EF" autofocus-bayonet-fitting lenses made by Canon image by Martin Taylor (Image rights) |
Canon's EOS (or Rebel) SLRs and DSLRs have the EF lens mount. That means a bayonet mount including electric contacts. "EF" means "Electro-Focus". It is not compatible with Canon's FD mount.
The lenses for the EF mount are often called EF lenses.
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Communication protocol[1]
The communication protocol between the camera is 8-data-bit, 1-stop-bit Serial Peripheral Interface Bus (SPI) mode 3. The pins, from right to left on the lens, are:
| Pin | Function | Notes |
|---|---|---|
| VBat | +6V to power internal lens focus motors | 150px
Present on all EOS bodies and lenses |
| P-Gnd | Power ground | |
| P-Gnd | ||
| VDD | +5.5V Digital logic power | |
| DCL | Data from camera to the lens (MOSI) | |
| DLC | Data from the lens to the camera (MISO) | |
| LCLK | Camera body generated clock signal (SCLK, CPOL=1) | |
| D-GND | Digital logic ground | |
| COM1 | Teleconverter common |
Only on most L-series and some macro lenses |
| EXT0 | Short to COM1 for 'Life Size Converter' and x1.4 teleconverter | |
| EXT1 | Short to COM1 for x2 and x1.4 teleconverter |
The information from the lens is used by the camera body for focusing and metering, and with digital camera bodies it is used to record the lens parameters in the Exif data in the images.
References
- ↑ source: Communication Protocol (Wikipedia)
- ↑ Canon EF focusing protocol on photo.net [1]
Links
- CNN about heavenly Canon autofocus lens fallen from the sky
