Showing results for 
Show  only  | Search instead for 
Did you mean: 

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

From canon rumors forum.....members have seen the same problem with the 600D

I'm beginning to think that they really have no solution....the engineers who designed this system have no understanding

of the needs of working photogs in the field. So now we have two camera bodies that are inadequate.

Mike the product expert was the first to pop in here. He collected some info and then disappeared, which spurred a bunch of speculation.    Then Mike disapeared and Naomi the moderator arrived.  but we've still got nothing so far -- that just tells me there is nothing new to share.  I sure wish were not the case though.


echelonphoto its hard to imagine that they  don't know;  they're just not talking.   Something as important as this, with a camera that disapoints the very target audience it was intended for and fails to fulfill the marketing narrative, shoulld be a big deal.  further silence suggests to me that we have a design flaw that might not be corrected at all until the mark IV arrives, but I sure hope I'm wrong on that...



1.  The test parameters given to the field to report on did not include scenarios that I believe the target audience for this camera is aimed at.


2. This issue was reported by testers and Canon chose to ignore.


3. The so called pro testers are incompetent and need replaced.


4. Everyone reporting this issue are wrong.


What’s it to be Canon?


LONG LONG overdue for a reply given the response time on the light leak issue.



Hi Guys,


     Keep the texts coming. I was on the job today....a wedding. I was able to keep the camera focusing faster

in one shot secret was to constantly prefocus at distance that I was about to take a photo...the

camera will focus faster if its close to the same distance as the prefocus.....this of course, rules out really

spontaneous photos....but if you think ahead it helps....not what I was planning to do with this body.

Just watched this video, by B&H, going through features of the new 600EX-RT flash


In the video, the guy (Canon product educator Eric Stoner) mentions that the flash will only have certain features with the 5D3, 1DX, and T4i, as these bodies have a new 'intelligent hotshoe'

Could this newly designed hotshoe be the problem/part of the problem?


As this problem doesn't seem to be affected by which flash is used (certainly between the 600EX-RT or 580EXII, the two models I have to test), I'm thinking that it must be something different with the camera body.


Prehaps this could be it???


It is mentioned at 0:36:53 (watch from 0:36:20 to hear what he has to say in context)


I hope that this might throw some light on the situtation.


I guess the biggest question is, does this issue occur with the 1DX, and the new T4i Rebel? (Is that the 600D that someone posted about above?)

Is there some way that the camera and flash could be set up that the flash throws out the af assist beam, when focusing, that doesn't involve using the hotshoe?
Just to see if that alleviates the problem?

I like seeing all the discussion and suggestions , but fundamentally Canon needs to address this directly, not just watch the user community chatter about  work-arounds.  A $3,000+ product that does not perform as advertized or within the marketed use cases should have generated a more meaningful engagment  by now. 

I'd like to ask the Forum, how you would intend to buy another Canon camera after this problem, thats if you ever do) EG: are you going to try and test it with a flash before buying~? for most people this is impractical, how are you going to walk into shop and ask to use a speedlite and get into a low lit sitation to then test the camera, 


for me personally I dont believe I will ever buy any camera again, unless I have fully tested it and this is a big problem, because this is going to waste a huge amount of time,  I dont think you can fully trust what forums say or product discriptions anymore after this problem.

I hear you louis. I had started a discussion on this on FM forums and was basically poopooed...most users said this was

in my imagination. Glad it has come to light here. Sad thing is one of my associates bought this before me and hinted at

the i could have held off...I bought anyway. Just talked to a local photog who was a long time Canon user and

switched to Nikon (F4) because of AF....of course that body is double  this price of the 5d.

Enter for a chance to win