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Problems with the 600EX-RT/ST-E3-RT system in radio.

I had FEC control with the transmitter, I don't any longer (ETTL mode) I don't even have it with a Speedlite as a master.
Also, yesterday all link lights were green but no fire with the ST as master. Had to use another 600EX .Got the setup home and the ST started behaving itself again but still no FEC control.

I'm not sure what is going on here. Everything matches - channels, IDs, Master>slave. Any ideas?


  • Can you provide more detail? You are in ETTL and the FEC is not showing up on the ST? If it does show up is the slave 600 is not responding to adjustments you are making on the ST? 
  • Yes. Adjustments made on the ST were not being transmitted to the 600. Now the FEC works but it's not "reading" so on the FEC diagram of either 600.
    This is both a 5D mkii and a 7D.
  • I have both cameras but never tried it on my 7D. I have not had that happen to me so far. So you are getting ETTL now. Obviously you are firing your camera to activate the ST so the signal goes to the 600 because you have done this before. Did you make any changes to the custom functions? I'll have a look at them just to see.

    You said you lost ETTL. This used to be known problem with the 580 EX II. The new locking foot design tended to make the flash wobble a bit and when the pins broke contact with the hot shoe the flash switched to TTL which was for film cameras. This varied from flash to flash. I have not heard this with the new RT system but I'm not sure what you meant by losing ETTL. Are you powering down the ST before installing and removing? I don't but I know I should be doing it.

    Sometimes doing a complete reset of the custom functions, etc and removing the batteries for 30 seconds have solved other problems for me.                    
  • Oh yes. Check your camera's flash menu as well.  
  • I should say that I lost control of ETTL, changing the settings on the ST but the 600 would not follow. It used to follow. After testing at home, the flash is now compensating but not displaying the change on the 600.
    I have not changed any of the custom functions. I have done a soft reset as well as pulling the batteries. No change.
    The one thing that worried me most was not being able to get the flash to fire at all with the ST. Had to use another 600.
  • And I haven't touched the cameras menu at all. Out of the box this system worked straight off. Now it's becoming unreliable.
  • Let me test that at home. When I'm using my system I'm typically in Manual and in group mode. I played with ETTL a few times just to see it work and as I recall I think it is normal for the 600 not to show FEC when you adjust it via the ST.  

    Do this test in ETTL. Try the with the FEC at 0, +3 and -3 and then check out the exposures.   

    I only use ETTL when the flash is on the camera and I'm shooting on the go.  
  • Looks like I can't edit my posts anymore. What I meant to say was - try this test in ETTL as well and we will compare notes.  
  • TrevTrev Moderator


    Yes, you can still edit your posts for up to a week. If you mouse over the post you will see a little 'cog', click on it and choose 'Edit' (see image)

    Yours will look different to this screenshot as being a moderator I can Edit/Delete any time.

  • TrevTrev Moderator
    This shows what you should see:

  • Mine does not show on the 600. About t not working I'd talk to Canon about that. I have not had any issues with the system.  
  • Neil vNNeil vN Administrator
    It does sound like there is a larger problem here than just mere settings on the flash and controller - time to send in for repair?
  • I'm still within my return date with B&H, Neil. Their return turnaround is very good, so I'm going to go that route. Plus, I'm going to pick up a 3rd 600.
  • Good call. I have 3 and the ST. They have always have worked well for me. B&H is very good to deal with. Good luck.  
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