11-12-2023 02:53 PM - last edited on 11-14-2023 08:38 AM by Danny
The EF 400 f2.8 is one of my favorite lenses and it ALMOST let me down yesterday at football. I typically shoot football with three bodies and lenses (1DX III bodies with 400 and 70-200 f2.8 glass and 1DX II body with 24-70 f2.8) and as I was setting drive and exposure I found the 1DX III body with the EF 400 wouldn't respond to setting drive, AF, metering, ISO etc nor could the menu or images be displayed. AF also wouldn't work although it focused fine in manual focus mode and the power focus ring and focus preset memory both worked perfectly. I removed the camera battery and tried again and got the same result. But without the lens attached, the body worked fine and putting the lens on another body resulted in the same non-responsive behavior.
I was about to switch that body to an EF 200-400 f4 "extender" which is also a nice lens but it doesn't focus quite as rapidly as the EF 400 which had worked perfectly at the last game. Since there was no error message, it was odd to have that behavior and the camera happily took photos without issue as long as I manually focused.
I decided to try cycling the ring of focus stop switches that are arranged around the far end of the barrel and after cycling each of them several times the lens fortunately returned to fully normal operation. When I got home, I mounted my 300 f2.8 on a body and held down one of the focus stop switches when I turned the power on and that combo behaved in exactly the same fashion as the EF 400 had while malfunctioning. So an AF stop switch staying closed when it shouldn't appears to have been the root cause.
The EF 400 performed flawlessly during the game and I have done a lot of testing today trying to get it to fail again without success. I will send it in for a cleaning and checkup in February which is a time of year when I don't use it BUT I hope by then to have gotten one of the four switches to fail again. I will probably ask Canon service to replace that array of four switches even though they may never malfunction again.
My criteria for camera gear is that it perform at a high level AND perform without glitches. My 1 series DSLR bodies and L series primes and zoom glass have always met that criteria and even after this episode I still have a trust filled relationship with the EF 400 🙂
So if you notice these symptoms (largely non-responsive camera with no error message) while using one of the "great white" lenses with AF stop buttons, try exercising the stop switches even if you normally don't use them. It may save you during an event. I always bring some spare gear but I prefer using my planned primary gear setup when possible and a little quick logical analysis made that possible yesterday.
Rodger
11-12-2023 05:42 PM
"When I got home, I mounted my 300 f2.8 on a body and held down one of the focus stop switches when I turned the power on and that combo behaved in exactly the same fashion as the EF 400 had while malfunctioning."
What if you do that again but this time turn Focus Preset to OFF?
11-12-2023 05:47 PM - edited 11-12-2023 06:30 PM
Same behavior, no impact.
I have the AF start button on my cameras configured for AF stop instead and if you hold this button down at power on (at least on 1DX series bodies), it behaves just like having a great white lens with a lens stop AF button depressed/stuck on.
Rodger
11-13-2023 06:15 AM
Got similar with my EF800. Happened twice. First time when I used lens protection that covered the focus stop buttons. Hanged all my cameras and also my friends R5. I pressed all focus stop buttons without any success. After 15 minutes everything went normal.
I don't remember the second time.
After that I turned Focus Preset to OFF and haven't had any issues, but I never ever touched the focus stop buttons anymore either.
11-13-2023 06:54 AM
Peter, during the time it was malfunctioning the focus preset still worked perfectly and I could even set a new memory position.
It sounds like the style/make of switch used has a bit of a reliability issue. Mechanically, they all had the same feel so it could easily be contamination within the switch. Hopefully they aren't prone to flaking of the contact plating which would cause a short in these normally open momentary switches.
I have 5 lenses with this AF stop array (4 primes plus the 200-400 f4) and so far none of the others have shown this behavior.
Rodger
11-12-2023 10:25 PM
Interesting. Almost sounds like an undocumented test mode.
11-13-2023 07:04 AM - edited 11-13-2023 07:05 AM
I only have EF800 and EF300/2.8L IS USM. Focus Preset from older super tele lenses will not work anyway with mirrorless and not in Live view with DSLR.
Give me an update when you have talked to Canon.
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