Some proof of 600-series speedlites and cellular interference causing link issues?

[rs-eos]

I stopped by a local photo studio today to test out my 600-series speedlites (first gen).    Wanted to see if they would drop links before working on a project there.

Interestingly, the owner mentioned before I started testing, that cell reception in the back area (studio) was quite bad.

I set up a total of six flashes on three stands (two with single flashes and one with my Foursquare to connect four together).   I was controlling the flashes via an ST-E3-RT (1st gen as well) on my EOS 5D IV.   I put all into the same group (A), and all were in manual mode (M).  Power set to 1/128.

Took several images and didn't experience any link drops.

I also turned off the transmitter several times throughout the test, then back on.  Within a couple seconds, all flashes had their links re-enabled.

I do wish I had tried other power settings, but I cannot imagine that having anything to do with the link drops.  When I did some work in my backyard a couple months back, I was using mostly 1/32, but I think also dropped to 1/64 at one point.

While this is nowhere near an exhaustive test by any means, it's kinda pointing more and more to cellular interference being the cause.

[deebatman316]

This possibly proves the link between 5G cell phone interference and Canon's RT flash system. I personally don't use off camera receiver speedlites. I also did a similar test with a 430EX III-RT (sender) and a gen 2 600EX (receiver) speedlite. I didn't have any problems. But the room I was in had no cell service at all. I did not try this test outside or in a room with strong cell service.

[rs-eos]

Something I just thought is that when I was in my back yard, if my cell phone at the time was still connected to WiFi, or if it had switched to 5G cellular.  I'll do more experiments over time and update this thread with my findings.

[deebatman316]

If I ever try the test outside I would probably have frequent drops. I live close to cell service tower less than a mile away. At night I can see the lights on the tower. So it could very well be related or be the problem.

[Anonymous]

Has anyone turned off their cellphone (or put in airplane mode) while the flashes are experiencing the dropped link issue to see if this is the problem? I've been reading through these posts on the dropped link issue, but I haven't seen anyone trying this with the cellphone.

[wq9nsc]

Canon uses the 2.4 Ghz band for their wireless flash system, the nearest cellular ranges are at 2.3 and 2.5 Ghz and those aren't in heavy/common use in the U.S.

But 2.4 Ghz is very heavily used for a variety of purposes including the most popular WiFi range, security systems, baby and other monitors, remote sensing (temperature, general weather, etc.).  And the fastest growing and most common interfering device in this range is the ubiquitous Bluetooth system. So the Canon wireless flash system is in a VERY busy neighborhood.

Link loss/link low reliability can occur both from direct interference on exactly the same frequency (which is why most devices can automatically or manually channel hop to find a suitable spot) AND from general loss of device sensitivity due to a noisy RF environment.  I suspect the latter is the problem with Canon devices and they aren't robust against a high level RF environment; this can occur due to poor quality on the receiving side and minimal power/poor antenna on the transmitting side.

Nothing is fully immune to this sort of interference but devices that transmit at the allowed limit with an efficient radiator combined with receivers that have a high dynamic range and steep rejection of just off frequency interference will be most reliable in terms of maintaining a link and minimizing packet errors.

A spectrum analyzer isn't an instrument photographers carry around but it will tell the tale of interfering signatures in an RF environment 🙂  I have used my Tektronix 7854 scope with 7L12 spectrum analyzer plug in for a lot of applications but so far NOT for finding flash interference.  But if you look at the 2.4 Ghz range in a typical public spot, the analyzer is going to show a lot of activity. 

And although MOST of the "garbage" from power supplies stays below the 2.4 Ghz range, some devices are so noisy that these unintentional radiators create problems.  The power supply in some LED bulbs is so noisy that using one in a garage door opener will interrupt communications with the controller (400 Mhz range for these devices) preventing the car remote from closing the door while the light is on after exiting the garage.  The power supplies used with home entertainment devices, digital devices, and home appliances are often far worse, particularly replacement units that don't even pretend to meet U.S./EU RFI regulations.

Rodger

[JLCKJC]

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@rs-eos wrote:

Something I just thought is that when I was in my back yard, if my cell phone at the time was still connected to WiFi, or if it had switched to 5G cellular.  I'll do more experiments over time and update this thread with my findings.

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Did you conduct any additional testing?

I've done some in the last few days playing with different channels and IDs and do see that some combinations are better than others in my home environment with a Wi-Fi router and two cell phones active plus the normal complement of other Wi-Fi connected devices online. I may look for a quieter environment (electromagnetically) to see if that makes any difference. Depending on the combination, drop times ranged from less than a minute to over 12 minutes. The ultimate test of this interference theory would be to put my three 600EX II RT's flashes and the ST-E3-RT (ver. 2) in a metal garbage can to create a faraday cage as the ultimate test. If the problem can't be resolved in some way or another that may become their final resting place. Has anyone tried this already?

[rs-eos]

Since that experiment I had conducted at the photo studio, I've only set up flashes at home once (this past weekend).  And things did not go well.  It was the first time I ever experienced link drops.  And it happened very often.   Camera (with ST-E3-RT v1 transmitter atop it) was always within 10 feet of the two flashes I was operating.  Each flash in their own group.

I was in the same location in my basement that I set up photo projects over the years.  Since the time of visiting the photo studio, no new hardware of any kind was added to our household.  So drawing a complete blank as to what happened.

However, our household does have a massive amount of devices connected to our home WiFi.  The area in the basement I was at is directly under my home office where the cable modem is at.   So it could be that on this particular day, my family was connected to more devices?  While we do have a dual band mesh network (2.4GHz and 5GHz) the vast majority of our devices are connecting to the 5GHz band.

It was the same behavior I had experienced when outside back in Spring.  Constant drops.

What I will attempt to do this coming weekend is have the family stop streaming anything (Airplane mode for everything; turn off TVs) and try the flashes.  Then, start up streaming again and see if any difference.

Ultimately though, there is still indeed an issue with the 600 series flash hardware and/or the ST-E3-RT transmitter.   I still have the version 1 transmitter.  Was toying with the idea of getting version 2, but I don't think that's going to solve anything.

Whenever I get my next camera (waiting on the EOS R5 Mark II), I'll either stick with Canon flashes (after ensuring no issues like what we're dealing with).  Or, may move to Profoto units.

[rs-eos]

Regarding a farady cage... I had been toying with the idea of building a large enough box (with fine copper mesh) to house the camera, ST-E3-RT transmitter and multiple flashes.   But in speaking with a photographer also very familiar with radio tech, he said it wouldn't work.  Even though all units would be in the cage, the cage itself would somehow block/interfere the signals.

[JLCKJC]

I believe I have proven the theory that the Canon ST-E3-RT (ver. 2) / 600EX II RT wireless system is dropping wireless links because of external electromagnetic interference. As I mentioned in another post I ran a number of tests yesterday with the ST-E3-RT sender and three 600EX II RT flashes, trying different channels and ID's. This testing was done in my home office not far from my Wi-Fi router. This home office has a single router and the normal complement of connected wireless devices (a couple of TV's, an Echo Show, one Samsung and one Apple cell phone). In this environment I experienced drops in less than a minute to at most 12 minutes. Some channel/ID combinations were better than others.

This morning I conducted a similar test on the same units. This time, I created a Faraday cage of sorts by placing all units (sender and Flashes) in a metal filing cabinet in my garage. This was in hopes of shielding them from most of whatever electromagnetic interference I have in my home office.

They ran flawlessly for over an hour before the flashes powered down as they were set to do. I then cycled the power on the remote, the three flashes woke up and reconnected and flashed when the test button was pressed. It's been over 30 minutes since the system was powered back up and still no drops. Each flash is in its own group; A, B, and C. A & B are in ETTL mode, and C is in manual mode at 1/128 power.

I believe this series of tests and the experiences that many of you have shared on this forum proves that the Canon flash system is unreliable where low to moderate electromagnetic interference exists. The system appears to be unsuitable for most venues in which it would likely be used where Wi-Fi and cell phones are in the vicinity.

This is an old design, but it's still being sold by Canon. The ST-E3-RT (ver. 2) was introduced a year or so ago and the EL1, which uses the same wireless protocol and has been reported to also have the same issues, was also introduced a little over a year ago. 

Now the question is, how do we get this information and test results in front of Canon so something might be done about this issue. At the very least they should stop selling this system until the problem is resolved in current production units. It's simply an unreliable system for real-world applications.

PS: As I post this note, it's now been 1 hour and 55 minutes, with no dropped links.

PPS: The flashes went through another auto power off as programmed and were again powered up when the ST-E3-RT was power cycled. Their wireless links restored as expected. I concluded the test after 3-1/2 hours with no dropped wireless links. I then removed the units from the Faraday cage (metal filing cabinet) and returned them to my office where they all lost their links in less than 5 minutes. Again, this points to external interference as the cause in a fairly common home Wi-Fi environment. This system appears not suited for use.