topic Re: RF 35mm F1.4L VCM with EOS R10 in EF & RF Lenses

RF 35mm F1.4L VCM shows "Err 70" on EOS R10

techshot — Sat, 05 Jul 2025 13:33:32 GMT

Hi all,

I have an opportunity to use RF 35mm F1.4L VCM together with my EOS R10. It would seem that they should be compatible, however, it seems like there is some issue with this combination. When I start the camera, it's almost like the lens fails to initialize or something. I keep hearing the mechanism making sounds inside, like it's trying something but it doesn't settle into anything. At the same time, I can't focus into anything and the camera is unable to take a picture. Eventually, the camera shuts down with "Err 70".

Both the lens and camera are on the latest firmware. Is this possibly some fault with the lens itself, or just an incompatible combination? The camera works fine with the kit lens.

Thanks in advance for a reply.

Re: RF 35mm F1.4L VCM with EOS R10

deebatman316 — Fri, 04 Jul 2025 15:52:12 GMT

I would try the lens on a different camera. All RF Mount lenses are compatible with all EOS R series cameras.

Re: RF 35mm F1.4L VCM with EOS R10

March411 — Fri, 04 Jul 2025 15:56:20 GMT

The RF lens should not have compatibility challenges. If you are in the states, have a Canon account and have registered both pieces on the Canon website it would be best to reach out to them directly at 800-652-2666. If they are not registered you may want to create an account and set them up prior to calling.

The support team will help you resolve the issue or help you with service.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Fri, 04 Jul 2025 16:06:04 GMT

Thanks for the replies. I'd gladly try with another camera, but unfortunately my R10 is the only one I have access to right now. Since there is not much else to consider in terms of compatibility, I should probably just contact support and try get a replacement. I already ensured also that there is no contact issues with the pins or anything like that, so that's also ruled out.

Re: RF 35mm F1.4L VCM with EOS R10

March411 — Fri, 04 Jul 2025 16:33:50 GMT

Contacting them is probably your best path with this challenge. They may walk you through a couple things in an attempt to resolve it and if that a bust they will offer service. I've never had a long wait time and support has always treated me well. I hope your experience is the same.

Re: RF 35mm F1.4L VCM with EOS R10

Waddizzle — Fri, 04 Jul 2025 17:23:01 GMT

The R Sereies body have feataure that goes by different names in different models, “Continuous AF:.

What this feature does is cause the camera to continuously auto focus while it is turned on. Disable it.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Fri, 04 Jul 2025 20:22:45 GMT

I ensured that it's disabled ("Preview AF" in R10). Sadly there is no response to these adjustments, even if I go full manual focus. The focus seemingly changes in response to gravitational pull when I gently tilt the camera+lens. Feels like the VCM is not able to hold it in place. At times, when I try to auto focus, the lens very briefly sharpens the picture, but then gives up immediately and goes back to blur. That initially made me thought that maybe I overlooked something that you'd need a more high end full frame to drive this thing, but that didn't seem right either...

Re: RF 35mm F1.4L VCM with EOS R10

deebatman316 — Fri, 04 Jul 2025 20:36:13 GMT

When the camera is off you’ll hear clunking from the lens. The lens uses floating elements. When the lens is powered by the camera. The elements are held in place by energized magnets.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Fri, 04 Jul 2025 20:42:50 GMT

Yes, that's what I read too. What seems off though is that its also clunking while the camera is on, although not as much, but I can definitely feel and hear it. While it does that, the focus point seems to change accordingly.

Re: RF 35mm F1.4L VCM with EOS R10

Waddizzle — Fri, 04 Jul 2025 21:45:56 GMT

“ Yes, that's what I read too. What seems off though is that it’s also clunking while the camera is on, although not as much, but I can definitely feel and hear it. While it does that, the focus point seems to change accordingly. “

Do you always turn the camera off when changing lenses? You should.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Fri, 04 Jul 2025 21:57:27 GMT

Yes, I do turn off wherever I remove or change.

Re: RF 35mm F1.4L VCM with EOS R10

deebatman316 — Fri, 04 Jul 2025 22:06:37 GMT

Can you post a video of the lens making this sound. Without a video we don’t know what’s normal and what’s broken. Without hearing it we don’t know what’s going on.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Fri, 04 Jul 2025 22:20:16 GMT

Definitely, I will post a video a bit later here.

Re: RF 35mm F1.4L VCM with EOS R10

techshot — Sat, 05 Jul 2025 11:44:35 GMT

I made two videos, first demonstrating the noise that the lens makes while sitting idle and camera is powered on. At the end of the video, I power off the camera so you can compare how it sounds between on/off. In the second video, I show the unresponsive auto focus and how the focus that I see on the screen changes when I tilt the camera slightly up and down. I'm also unable to take a photo. Not in the video, but a few times I manage to make the shutter click, followed by immediate "Err 70".

Video 1, unexpected noise

Video 2, auto focus

Thanks for having a look and let me know if this indeed looks abnormal, or if I've severely misunderstood something.

Re: RF 35mm F1.4L VCM with EOS R10

ebiggs1 — Sat, 05 Jul 2025 15:19:51 GMT

"Yes, I do turn off wherever I remove or change."

That's not the problem. The first contact to break contact when you remove a lens is the power and the last one to make contact when you mount a lens is the power contact. The reason some say to turn off your camera is because of the possibility of static charged dust getting in.

From your vids, I think the IS in the lens is faulty so the lens needs servicing.

Re: RF 35mm F1.4L VCM with EOS R10

deebatman316 — Sat, 05 Jul 2025 16:23:05 GMT

Actually not completely true. With RF lenses they have to “park” internal mechanisms on power down. They also stop down the aperture to the smallest aperture and then a little more. This is to prevent the image sensor from being exposed. Not all R series cameras close the shutter on power down to prevent dust. Or light to be exposed on the image sensor when the camera is powered off. Adapted EF lenses also stop down to the smallest aperture setting. When the camera is powered off. This is what Canon USA’s response was when removing lenses with the camera on. It’s best to turn off the camera. Or an error message could pop up. When the lens is refitted to the camera body.

Re: RF 35mm F1.4L VCM shows "Err 70" on EOS R10

techshot — Wed, 09 Jul 2025 11:04:46 GMT

Update. I've obtained another lens of the same model. This one works very well and takes beautiful, sharp images. I'm now in the process returning the faulty lens. Thanks everyone for the replies and help!

Re: RF 35mm F1.4L VCM shows "Err 70" on EOS R10

March411 — Wed, 09 Jul 2025 15:27:25 GMT

Good to hear that you got it resolved and you have a working lens!