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5D3 + AF assist beam = slower focus


Hello All,


While I am new on these forums I have been on the Canon Rumors Forums for a few years now, 


I really wanted to bring this too the attention of you and Canon as it is simply a highly important problem, those of you that don't know, the 5D3 suffers serious focus locking issues when a Canon speedite is attached in Low light, the AF assist beam causes lag with the AF from the 5D3, this makes it virtually impossible to achieve focus in low light when the speedlite is attached, I wanted to bring the topic to this forum, so I have pasted a link to all the discussion we have already had about this problem at Canon - see below



Please help in letting Canon know this is a very serious problem and effects the cameras performance in most working environments when a speedlite is attached and working in low light, conferences, nightclub work, weddings etc, and can stop the photographer completing the job or task.




180 REPLIES 180

Excellent;  thank-you Crista.  would you be at liberty to clarify the battery issue that appears to have been introduced with this revision?

Should we start a new thread on user results in the the EOS category or just continue here? There were mutiple threads on this at one time.  

Just installed the 1.2.1 firmware update in my 5D3 and it does seem to focus more quickly in low light with the IR assist.  I have a gig tomorrow and will be able to confirm after that.  


I would REALLY like to know when this will be fixed on the 1DX.  It's just as bad as the 5D3!

Keep us updated.

There is a pro wedding photographer at the POTN forums who is going to give the 5D3 a try this weekend. He has been shooting in AI Servo was a work around but prefers One Shot when Servo is not required. I'll update his findings as well.   

I shot two gigs last night in very low light with the upgraded 5D3 and I am extremely happy.  The new speed to locl AF makes it feel like a different camera -- probably up to half the time to lock than before I upgraded.  I can't vouch for any of the other aspects of the firmware upgrade, but the AF lock speed with IR focus assist is WAY better now.


Canon:  Please get the fix out for this on the 1DX ASAP!  It doesn't seem reasonable to me that your flagship camera is lagging behind lower-end cameras for performance updates.

Sounds good and thanks for the update. There are now 2 pro wedding photogs at POTN shooting weddings this weekend. I'll post thier  responses.    

Posts the 2 wedding photogs.  I trust these people. 




This is me reporting back after the wedding.

Yeah...pretty big difference. 

I never really complained about slow AF with the assist beam. I always felt it was deliberate, but nothing close to being a show stopper.

That said, even I noticed the improvement. Extremely responsive at the reception I was shooting tonight. 





seemed to be much faster to me as well. Very responsive. Like it a lot.

Hi everyone,
We have another important update on this topic. A firmware update for the EOS-1D X has just been released. Firmware Update Ver. 1.2.4 incorporates functional improvements including AF speed improvement when using a Canon Speedlite’s AF-assist beam.

To learn more and download the update, click here.

i can categorically confirm this firmware hasnt fixed the issue for me....


its is particularly bad on my 5D3 with 70-200mm F2.8 IS USM II


Am an experienced wedding photographer... and this camera is driving me insane.. low light focus and usability is just non existent. 


had a wedding on the weekend... and i cannot notice any difference pre and post firmware upgrade at all!


i cannot get this thing to lock focus... it just hunts and hunts.... and it happens on both my 5D3 bodies with a prime sitting on one and a zoom on the other... with 580 EX II sitting on both. 


sorry not happy with the firm ware fix at all

click here to view the press release