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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

I work as the inhouse photographer in a few different nightclubs 6 nights a week, so I run into this problem alot!!


5D Mark 3 + 580EXII or 600EX-RT both seem to suffer this problem for me.


Happens with:

16-35 L MKII

24-70 L MKII


at all focal ranges. (I'm not saying that it's only these lens, but these are the ones that I use on this camera)


Center spot focus, expanded 8 and 61pt focus or any other combination of (as far as I've found so far)

Eval, Center Weighted and Spot all problematic

ISO 100-6400 all problematic

AV mode TV mode and M mode all problematic.


To wrap it up, I haven't found any mode, or setting that aleviates this problem... If I could find a setting or model/dial/or knob to change to fix this, I'd stick to it for shot necessitate the AF beam.


I can't replicate this issue at all on my 7D in the same, or any other environment.


Guys.....this is ridiculous....who do we call....our livelyhood is being affected here.....I just don't see how so many

photogs are raving about the 5d3 AF!  Are there two different versions going around here? I don't want to own

a 3000 paperweight...which is just what the camera is to me right now


Have done the comparisons between Nikon and Canon....and 


1) Still prefer the reviews from various sources regarding the Canon

2) Have a few pieces of equipment that are for the Canon and would require a wholesale refit, which as you will appreciate then makes the savings via an upgrade path futile

EOS 5D MKIII + EF 24-105mm f/4L IS USM, Sigma DG 150-500 5-6.3 APO HSM, , EF 55-200mm 4.5-5.6 USM, Speedlite 430EXII

EOS 350D, EFS 18-55mm

Yeah. No AF problems with the D800 and D4 Smiley Wink

yes but have problems in other areas....moire, aliasing etc

EOS 5D MKIII + EF 24-105mm f/4L IS USM, Sigma DG 150-500 5-6.3 APO HSM, , EF 55-200mm 4.5-5.6 USM, Speedlite 430EXII

EOS 350D, EFS 18-55mm

Still no mention for a fix for April..

I have been frustrated with this issue as well.


I had no issues with 580exII on Canon 7D using 17-55f2.8 IS


I have missed quite a few shots with 5D Mark III and 24-105 f4 IS using 580EXII due to focus lag when AF assist beam used. I recently purchased 600EX-RT due to claim of better 61 AF point assist. No difference, it still slow in auto focus. 

Then did a search and found this thread. This is a real issue for me As well as most other posters on this thread.



Isn't it frustrating, though? You spend years perfecting your style and building your business...then you go the extra

step and spend the money on the latest equipment so you can even better your product....and poof! wind up

screwing up important images because the new equipment is worse than the old....then you go out and spend more

money on expensive accessories (flash) to hopefully recoup your composure and confidence and it falls flat anyway...


.........ARE YOU LISTENING ......CANON???......This isn't going to go away!!!

This is a BIG issue, Canon please fix this now! My 5D I works way better.


My details are:

Any mode,

,24-105 at any length

580 EX I




click here to view the press release