Canon ETTL protocol

This is a continuing story from and previous posts.

Good news!  I found out today that the drop of CLK to ground (after command message 0xb4 0x3d) before the “X” pin drops is exactly 4.00 msec.  This has been measured several times.  This is good as we now have a leading indicator when the flash is requested to do its job!   This is sufficient time for even wireless modes.  Of course I don’t really have the data of the shutter curtain positions relative to the “X” pin.

I’m working on a collective document that describes everything that I’ve found so far.  This would be easier for people to look at than these piece-meal postings.




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4 Responses to “Canon ETTL protocol”

  1. Stephen Eaton Says:

    Congrats Bill, something of a baseline for us to try for with the Strobit Triggr.

    Now to fool the Body that is has a High Speed Sync Flash attached….

  2. Canon E-TTL Timings » Everything Robotics…….and then some Says:

    […] Post: No TweetBacks yet. (Be the first to Tweet this post)   « Strobit Triggr and Canons […]

  3. zinmirai Says:

    Following this very closely.. keep up the good work :]

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