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EOS R5 Err 70


I just received a new EOS R5 and out of the box I was getting an err 70 lockup. I thought updating the firmware would resolve the problem but the err 70 continues. I have now received a message 20 or 25 times over the course of 100 frames. Is the a comen problem?




This is not common.

Is your battery fully charged?

Start by performing a factory reset of the camera.

What type of memory card(s) are you using and were they formatted in the camera?

What type of lens are you using on the camera?


Bay Area - CA

~R5 C ( ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, +RF 1.4x TC, +Canon Control Ring, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve ~Windows11 Pro ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8
~CarePaks Are Worth It

Good morning, the battery is fully charged, I am using a SanDisk Extreme PRO CFexpress Type B and it is formatted. I am using a EF lenses with the Canon EF-EOS R mount adapter. Canon EF 24-70mm f/2.8 L USM, Canon EF 17-35mm f/2.8 L USM, and Canon EF 70-200mm f/2.8 L USM. I will attempt to reset.


The problem is with the Canon EF to R Mount Adapter.  I shoot timelapes and get ERR 70's all the time when I'm using an EF lens on that adapter. The problem seems to occur when the camera needs to control the aperture.  When I set my aperture to it's largest setting - in your case F/2.8, I never get the ERR 70.   But if I set it to any other aperture (3.5,4, 5.6, etc) I will eventually get an ERR 70 at some point during my timelapse - unless of course I stop my timelapse before it occurs.  It usually takes 150+ frames before it shows up.  I've tested this with Canon and 3rd party lenses. I've also tested this with a variety of SDXC and CF Express Type B memory cards, and with different batteries.  You seem to be getting the ERR 70 much more often than even I was getting them. 
I just purchased the Canon 24-105 F/4.1 - F/7 lens and no lockups even after 1000 frames of a timelapse.  I also just purchased a Rokinon 14mm AF RF Mount lens and again no ERR 70 lock ups.  There is some communication issue with their adapter and EF lenses.  I've reported my findings to Canon and despite that all they did was replace my main PCB board (twice) and it didn't solve the issue.   So for me it's not the battery, it's not the memory card, it's not the main PCB, it's not the battery remaining - its the EF lens with their adapter.  

Now I have read reports of people getting lock ups even with RF lenses but this seem to have something to do with back Autofocus which I believe firmware 1.5.1 was supposed to correct(?), but I have not yet had this issue at all and I shoot a LOT of frames.  However, most of what I shoot is with manual focus (for timelapse).


I'm getting this, too. It seems to happen more frequently when using an 430EX RT III flash. I used a 5D MKIII for years and NEVER had any kind of problem. It just ran flawlessly. This R5 seems to be very wonky. I only use Canon lenses and on this just RF lenses, so this should also work flawlessly in my book. I've had issues running a 24-105 ƒ4L and a 24-240.

I also get errors - not error codes - but errors when using the flash on AV mode. The SS is preset to 1/250, so it should just adjust the ISO, but it often doesn't and the images come out too dark.

Anyway, just reporting this here to say "my R5 is wonky, too!" 😖

You've provided an important "clue" to this forensic analysis (that Canon seems not to be doing) regarding "seems to occur when the camera needs to control the aperture." This seems to be what's happened in my experience, coupled with using a flash 430 EXIII RT... Anyway, thanks. It'll help me be on the lookout next time it happens.


I Googled “EOS R5 Error 70” and got a lot of hits. Most of the reports seem to point to a defective main circuit board or motherboard. I would return the camera to the seller for an exchange or refund, or send it to Canon for warranty service. 

Mike Sowsun

I sent this in to Canon for the Error 70, they replaced the main circuit board, still get the error every 50 frames or so, annoying!


The problem is not restricted the EF to R mount adapter. I took delivery of a EOS R5 4 days ago. I have used only two new R mount lenses (RF 24 - 70mm f/2.8 and RF 85mm f/2 Macro IS STM). On each of the last four days I get the dreaded Err 70 error message over half a dozen times every day. Yes, turning off the camera and removing/reinserting the battery resolves the problem, but it happens consistently with both lenses. I am returning/exchanging the camera at B&H. I have never experienced anything like this with many years of experience with Olympus, Sony & Leica. This is my first Canon. I was so excited and greatly disappointed with what seems to be a problem experienced by many Canon users on a variety of Canon cameras. What gives??? How widespread is this problem? What does Canon have to say about the cause and the fix???

I know that it’s possible to get an Error 70 for  reasons other than what I am stating.  Error 70 is a communication error and normally has to do with memory card writing issue or lens communications.  But in my case I had two main PCB’s replaced and both times the error would still show up at some point in every timelapse (when not shooting wide open).   Since I have been shooting with RF lenses I have shot thousand of frames and at least a dozen timelapses and have not had a problem since.   So for me the adapters and my EF lenses were causing a communication issue when the camera had to control the aperture of the lens.  For those that don’t shoot timelpase it might only show up once or twice in a year - but for me it would show up everyone I shot a timelapse (but not usually until after 170 or 189 frames.  

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