topic Re: Camera will not autofocus when 200-400mm f4 is connected in EF & RF Lenses

Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 16:47:30 GMT

Hi,

I recently bought a used Canon 200-400 f4 lens and have used it for several hours of sports shooting with no problems. Last night while shooting it stopped being able to autofocus and none of the buttons on the camera would work. I tried switching bodies thinking it was my camera, but the same thing was happening. After lots of experimenting, I could get it to work right if I disconnected the lens from the camera while the camera was powered on and then reconnected. It would only work correctly for a short time though. Anyone have ideas on what might be wrong or fixes I could try?

Thanks,

Jessica

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 16:50:00 GMT

The lens should be returned if its not working. Since its a used lens.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 16:54:53 GMT

Yes, if there is not an easy fix, I will definitely return. Hoping there is an easy fix though.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 17:03:13 GMT

When this happens does the camera still report lens aperture. If the camera displays F/00 or F/-- that could mean the flex cable in the lens has failed. Or the lens contacts may need cleaning. But this rarely fixes the problem. Also what camera are you using this lens with. It is also not an easy fix. Canon can replace it if the lens is still supported by them. But get a quote first before repairing if its still supported by Canon.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 17:03:19 GMT

Yes, it still reports the aperture. I can actually still take pictures too and use the manual focus.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 17:29:46 GMT

Are you hitting the AF Stop button on the lens on accident. Also what camera are you using this lens on. EF 200-400mm lens manual PDF

Re: Camera will not autofocus when 200-400mm f4 is connected

wq9nsc — Fri, 07 Apr 2023 19:58:01 GMT

I was thinking that it is also possible that one of the array of AF stop buttons on the lens is jammed if he isn't touching it. The array of AF buttons around my L telephoto primes is a feature I really like but that might be a part of the lens most subject to damage if it was heavily used in bad weather/sea side conditions.

Rodger

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 20:47:11 GMT

No, I am not. It has happened on my 1DX Mark III and my R5 with the lens adapter. Same behavior on both bodies.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 20:47:45 GMT

Would that prevent all of the buttons on the body from working as well?

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 21:00:15 GMT

Does the camera report MF when this happens. The AF stop button will cause the lens to act this way on both cameras. Even if it is intended or not. That also doesn't mean that the AF stop button is functioning correctly either. In the camera's custom functions menu. You can turn off the AF Stop button to see if its causing the problem.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 21:50:42 GMT

The camera does not report MF.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 22:09:19 GMT

Then it's likely the AF stop button.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 22:55:06 GMT

Indeed it is. I turned it off with my R5 and worked perfectly. Unfortunately, I cannot turn that button off with the 1DX Mark III.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Sat, 08 Apr 2023 00:29:39 GMT

I'm surprised by that. On my retired EOS 40D. A button could be assigned for that function or turned off. But my 5D Mark IV only gives me a choice to remap it to a different button. My retired EOS 40D had the "*" button set to AF Stop. I experienced the same problems you did. After I changed what the button did back to default. I never had that problem again. My uncle used to own that camera before I did.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Fri, 07 Apr 2023 23:07:35 GMT

I can map it to something else (another function) but OFF is not an option for that button when on my 1dx. I was able to do it on the R5... I now have to decide if I want to return it, pay to fix it, or only use it with my r5 since I never use those buttons anyway... That is my least favorite option.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Fri, 07 Apr 2023 23:51:54 GMT

Where did you get this lens from does it have a warranty on it. If so it can be returned because the lens is NOT functioning correctly.

Re: Camera will not autofocus when 200-400mm f4 is connected

jshfoto — Sat, 08 Apr 2023 00:18:29 GMT

Yes, I can return it. However, they have no other used ones in stock right now and I need the lens for my business. Hence why I am trying to figure out if it's worth getting fixed or if I need to return it and then hope another one pops up.

Re: Camera will not autofocus when 200-400mm f4 is connected

deebatman316 — Sat, 08 Apr 2023 00:31:04 GMT

I would check and see if Canon supports this lens first. If they still do get a quote first before a repair is made.