Additional functions supported by ST-E3-RT(Ver.2) vs ST-E3-RT
Cameras released from 2020 (e.g., EOS-1D X MkIII, EOS R5/R6 and later, but excluding EOS 850D) Compatible cameras may need the latest firmware update.
Compatible cameras may need the latest firmware update.
Wireless second curtain sync
Low Power (1/8192) Minimum flash output of 1/8192 possible with Speedlite EL-1 only (1/128 with high-speed sync).
Minimum flash output of 1/8192 possible with Speedlite EL-1 only (1/128 with high-speed sync).
FE memory Flash output amount may slightly differ between that of E-TTL autoflash and manual flash
Flash output amount may slightly differ between that of E-TTL autoflash and manual flash
Other cameras from before 2020 (e.g., EOS-1D X Mark II) Compatible cameras may need the latest firmware update.
Compatible cameras may need the latest firmware update.
Wireless second curtain sync
Low Power (1/8192) Minimum flash output of 1/8192 possible with Speedlite EL-1 only (1/128 with high-speed sync).
Minimum flash output of 1/8192 possible with Speedlite EL-1 only (1/128 with high-speed sync).
FE memory Flash output amount may slightly differ between that of E-TTL autoflash and manual flash
Flash output amount may slightly differ between that of E-TTL autoflash and manual flash