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Canon 5D Mark3 Major Focus issue on sky




Need major help!



Bought Canon 5D M3 less then 2 months ago put 20,000 images on it. 7 days ago  it wouldnt let me view images after then were taken. No buttons would work either. Had to take battery out to fix the issue.


3 Days ago all of a sudden it started having focusing issues. In all modes ( I always shoot AV) it will not focus on ANYTHING AT ALL IN THE SKY flying. One shot AI focus and AI servo. It has major issues focusing on anything in the sky either. It kinda tries sometimes but mostly doesnt even try to focus. Generally if it cant find something if will focus to infinity and back until it find it. It wont do that.


Let me repete, It wont focus at all with an object in the sky on AF all 61 points. It will somewhat try half ass like just hair then doesnt do anything. Its like the AF motor is screwed but that in the lens not the camera.


With a dark subject background it will focus but very slowly. I have cleared all custom settings in both places.


My main lens is a 600 F4 IS. But I am having the same issue on all my lenses with this camera. 100-400, 70-200 2.8 IS 11 24-70. I put these lenses on my 7D and all focus fast and no focusing issues. ( The 7D is such a terrible camera, nothing is sharp but thats another issue)



Need major help I am out shooting for the past 2 months and have 3 more weeks of solid shooting to go with 0 down time! I cant send my camera away!!!






Hi jorelcuomo!

Thanks for posting in the Canon Forum! The Forum is not intended for immediate help, but a place to allow for the Community to give you assistance and feedback. If this is an urgent support need, please CLICK HERE to reach our friendly Technical Support Team by phone or email.



You basically have just about the top performing focus system on the market (the 1D X is nearly identical but improves upon how the Canon iTR system works.)


The 5D III ha a _lot_ of focus modes.  Picking the wrong mode could easily explain this.  It's not a matter of "one shot" vs "ai servo" (you want AI Servo ... but there are so many other things that configure how the focus system works in this camera.)


For example, if you are using "spot" mode then the focus point is actually reduced.  This mode is intended to focus on subjects with high detail and contrast which are precariously close to emage elements at a different focused distance (to avoid focusing on the wrong thing.)  But if the subject fails to have adequate contrast, the camera will struggle to focus at all.


Any of the other modes will be better... but the "Expand AF area" modes borrow focus assist from the selected point to improve the ability to find contrasty edges to lock focus.  


Canon has a great document which explains the focus system on this camera and you'll definitely want to make sure you download and read it.  


You can find that document here:


The PDF link to download the document is near the bottom of that page.




Tim Campbell
5D III, 5D IV, 60Da

thanks but this is a new problem to the camera as it was working fine before. Its getting sent to Canon shorly