topic Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5 in EF & RF Lenses

Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

ctschuwei — Fri, 16 May 2025 23:28:00 GMT

Hello! I just picked up a used Sigma 24-70 f/2.8 DG OS lens (the newest 24-70 version, 2019 I think?) and it works just fine on manual focus, but the AF is not working. It was giving me an Err 01 code, and so I researched and found that the most common solution was to update the lens firmware. Fast forward, I ordered a Sigma dock and tried to update the lens firmware, but it was already at the newest firmware version 2.05. So I reset the custom AF/OS settings, still same issue.

Then I checked my canon r5 to make sure the firmware was up to date on that one, and now the moment I connect the lens to the the camera, it gives me the Err 01 code.

I am using an official Canon branded EF-R converter. I have tried it on an EF lens that I have and it works perfect, no issues whatsoever.

Has anyone else experienced this? Is it a faulty lens issue? Do I need to take the lens in? Any advice? Thank you!!

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

deebatman316 — Sat, 17 May 2025 01:26:17 GMT

Is this the original R5 or the R5 Mark II just want to confirm the correct camera. Some older 3rd Party lenses may not work well with a newer camera. Especially when being adapted. Also we need the Full Model name in question.

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

shadowsports — Sat, 17 May 2025 01:45:55 GMT

Greetings,

Sigma 24-70 f2.8 (A017 variant) - I owned this lens for over 5 yrs and used it successfully on my R5 C. It worked perfectly in photo mode and near perfect in cinema OS, but AF was a little slower when using for video. It was still very acceptable. I bought it over the Canon EF equivalent because the Sigma had IS. I still have my USB dock.

I purchased the RF 24-70 f2.8 a few years ago. It's beautiful. I recommend it.

You may want to consider contacting Sigma Support and see what they say. They may suggest you send your lens in.

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

ctschuwei — Sat, 17 May 2025 05:24:57 GMT

Original R5! And full model name for the lens is Sigma 24-70mm f/2.8 DG OS HSM Art. Thanks!

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

ctschuwei — Sat, 17 May 2025 05:26:49 GMT

Thanks Rick, I'll definitely reach out to Sigma Support. Cheers!

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

ebiggs1 — Sat, 17 May 2025 16:57:59 GMT

OK, here's what you do. First do a full reset of the camera even custom settings. Everything. Error 1 is probably the most common error and it means the lens and camera can't talk to each other. Canon will tell you to clean the contacts on both the lens and the camera but In my years, decades, of experience that rarely to never helps or works. It's cheap and easy, so why not. Just make sure you do it correctly. You checked the FW on the lens and again probably not the problem. Checking the FW of your camera will do nothing as Canon does not make FW for off-brand lenses. Why would they? Do the full reset and if it doesn't correct error 1 the lens most likely needs repair.

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

Waddizzle — Sat, 17 May 2025 17:26:20 GMT

Have you tried a different EF mount lens with the mount adapter?

Do any RF lenses function properly?

Re: Sigma 24-70 f/2.8 DG lens giving Err 01 on Canon R5

ebiggs1 — Sun, 18 May 2025 14:00:42 GMT

"I am using an official Canon branded EF-R converter. I have tried it on an EF lens that I have and it works perfect, no issues whatsoever."