Flaky Tethering with EOS R5 Mark II

[Nightfae]

I recently bought a Canon R5 MK 2 which I mainly use in studio with a tethered setup.

The camera is tethered via a TetherTools USB-C to USB-C cable to a M2 MacBook Pro using Lightroom Classic.

Currently (05/2025) the camera is not appearing in the supported list of LR, however, the last update added the support - so the camera is basically detected and the connection is working.

The odd problem is, that Lightroom (and also Capture One, which I tested) takes a long time to detect the camera - and if the camera goes into standby - or is switched off temporarily, the connection sometimes cannot be re-established - or it takes forever until it is.

If that happens, the camera shows the charging symbol or just "busy" on the displays.

I tried around and found out, that the culprit seems to be the negotiating between camera and device:

The camera can either charge via USB-C or transmit data via USB-C - but not both at the same time. When connecting, the camera has trouble deciding whether it wants to use the USB-C power delivery to charge the battery or if it wants to use the data lines.

Unfortunately this negotiation seems taking forever and sometimes even fails.

A very simple hack to solve the problem is to strip power delivery. This can be done by using a cable that is not capable of this (like a USB-C to USB-A cable) - or by adding two adapters that strip power delivery from the connection.

I have bought a USB-C plug to USB-A 3.0 socket adapter in which I plugged a USB-A 3.0 to USB-C socket adapter.

I can plug this contraption into my MacBook and the tether cable into it and the issue is mostly completely gone. The camera will be detected immediately afterwards. Occasionally, it will show the battery symbol on waking up, but a half press on the shutter immediately skips this and establishes connection.

This of course is not optimal. 

Is there any way to switch off USB charging on the camera, that I did not find? Otherwise, I would like to ask for a firmware feature to implement this, if the hardware allows for that.

[Waddizzle]

Do you have any documentation supporting the charging cable issue?  Canon has a special cable for charging.  A conventional USB data cable charge the camera,  Try it!

This fact points a finger at the Tether Tools cable that you are using.

Is the camera being powered by an AC adapter?  If so, try testing the setup with the camera on battery power.  

[ebiggs1]

" If so, try testing the setup with the camera on battery power."

I would do that. I don't have a R5 Mk II but I tether my 1 Series a lot of the time. In fact I do so at every Senior photo shoot. These take a few hours to complete. I have never had an issue with LR Classic. I use a simple active USB and the camera's battery power. I have even been a fairly long distance away from camera to computer sometimes.

If your M2 MacBook Pro sees the camera I don't see why it would present a problem to LR since that is where LR gets it. However, again I use a PC laptop with Win 11. Mirrorless and Mac's may operate differently.

[spvsandy]

Problem is cable  Tether tools usb c optima cable blocks the charging function therefore allowing tether.

Used my r5 via adapter usb a to c  plugged into computer usb a and worked fine with a tether tools boost

good lusk

[Nightfae]

My problem is not that charging is not working. My problem is that tethering is not working fine. The problem persists with a bunch of different cables that I tried, although all of then were able to do power delivery.

[Nightfae]

That is pretty much the same that my adapter does. However, that is a pretty shabby workaround.

[Nightfae · Accepted solution]

After getting my hands on a Canon DR-E6P dummy battery adapter, I can confirm that the issue seems to be cause by the camera deciding to charge the battery instead of tethering.

If the dummy battery is used, the USB-C to USB-C cable can be used without any hassle and without any handshake issues where the camera decides it would rather charge.

While this of course now works, it also means if there is no other way to disable USB-C charging in the camera, using the camera on battery to tether via the fastest option (USB-C to USB-C) becomes unreliable.

Furthermore the issue seems to be worse, the emptier the battery gets. I was thinking I am crazy as the initial connection would usually work fine. This is with a full battery, so no attempt to charge. And then it seemed getting worse the more I was into the session. Changing Batteries usually would work fine. Now all of this makes sense.

So the solutions would be:

1. Use a dummy battery and USB-C to USB-C Cable
2. Or use a stripping adapter as described
3. Or use a USB-C to USB-A cable (which is basically a variant of 1)

[SouthportKen]

Is there anything on the horizon from Canon for the R5 Mk II tether issue. There is a lot of ways to get around the problem , most are just work arounds. Whether in the studio or in the field tethering is critical to my business. You loose the client REAL fast if they can't results. How could Canon miss this requirement ????  Maybe I'm just venting but at this point all I have is a $4300 anchor. Any inkling of news from Canon on a future fix?   It's amazing that my 7D Mk II, 5Dsr, and 5D Mk IV tether without any problems

[Anitas_nl]

Hello,

Unfortunately this was not a solution for me.

Using a Canon EOS R5 Mark II on firmware 1.0.3 with Canon PD-E2 and DR-E6P coupler. Tried all kinds of usb cables (usb-c to usb-c and usb-c to usb-a) and the original cable and a Tether Tools Optima cable. Also new usb-c to usb-a cables at different lengths (1 meter to max. 2 meters).

All power saving options in the camera are off except for the EVF (kept default). Also all network abilities are off in the camera.

Using a usb-hub with its own power supply does not solve the problem either.

Using Helicon Remote and Canon EOS Utility. Spoke to developer of Helicon Remote but found no solution.

Please, I need a stable usb connection between camera and Windows 11 desktop computer.

When switching off the camera the lcd screen shows the message "saving ... remaining images: 1" forever. I have to cut power or remove memory card.

Regards,

Anita

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@Nightfae wrote:

After getting my hands on a Canon DR-E6P dummy battery adapter, I can confirm that the issue seems to be cause by the camera deciding to charge the battery instead of tethering.

If the dummy battery is used, the USB-C to USB-C cable can be used without any hassle and without any handshake issues where the camera decides it would rather charge.

While this of course now works, it also means if there is no other way to disable USB-C charging in the camera, using the camera on battery to tether via the fastest option (USB-C to USB-C) becomes unreliable.

Furthermore the issue seems to be worse, the emptier the battery gets. I was thinking I am crazy as the initial connection would usually work fine. This is with a full battery, so no attempt to charge. And then it seemed getting worse the more I was into the session. Changing Batteries usually would work fine. Now all of this makes sense.

So the solutions would be:

1. Use a dummy battery and USB-C to USB-C Cable
2. Or use a stripping adapter as described
3. Or use a USB-C to USB-A cable (which is basically a variant of 1)

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