600RT Flash bug in new Canon 5DIII firmware.

Started May 12, 2013 | Discussions thread
David Hull
David Hull Veteran Member • Posts: 6,022
Re: 600RT Flash bug in new Canon 5DIII firmware.


Hello. Here is a way to do a quick test.

Make sure your IR is turned on, on the flash.

Put the camera on ISO 3200, shutter 200. (even though it does it at ANY ISO, and ANY SHUTTER, this is to make sure its not your batteries recharging that is causing the flash NOT to fire)

Make sure you are in AF. Make sure the room is DARK, so the IR is needed to focus. When the IR is not needed,  turned off or in MF, the flash problem does not happened at all.

Take about 50 shots in NON-HS sync. If you take then at about 1 shot per second, the flash should fire every time (make sure you batteries are fresh in the flash, etc)

You will find some of the times the flash does not fire. But this is the RARE side of the error. I found a way to make it happen more often.

Set the flash at 0. Turn on HS sync, then -1 the flash (I set the flash with the wheel only to + or - it, instead of hitting the center button, then the wheel)

You 1st HS sync flash 1/3 of the time will NOT fire, and sometimes it will do it twice in a row. I had over 10% of my shots last night MISS, as in the flash did not FIRE.

Most of them was with HS SYNC OFF, and in a dark room.

Both of my cameras had flash fire inconsistances, no matter the lens, or body. AS SOON as I downgraded the firmware back to the older version, the problem disappeared completely.  The new firmware camera STILL DOES IT.

I am sure it is due to the change in the IR that WAS added to the new firmware. Since not everyone shoots with the IR light on, shoot with a 550 or 580 flash, they may not have the problem. Someone with a 430ex does not have the issue, and it looks like it does not happen on the 580.

The ONLY pattern I have found is 5D3, newest firmware, 600EX-RT, IR on, and in a dark room that needs the IR for the camera to focus. This is why I missed it before. A lot of my shooting after the upgrade was outdoors..  It took a night wedding to run into it.

David Hull wrote:

So, I have a 5DIII and two 600EX-RT Flashes but having read through all of this, it is not really clear what the problem is of the steps to reproduce it.  Can you put up a description of the exact issue and the steps needed to reproduce it?  I looked and I don't have the old FW for some reason.

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I'll try to find a bit of time to try this.  I did some initial testing with the hew FW and I never noticed it not firing but I didn't fire a lot of shots like that.  I did notice that it changes its red pattern depending on how the AF point is set.  What AF point setup do you have selected (CP, I presume?).

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