EOS R5 Mark II + RF 600mm F4 L IS USM switching to manual focus

[Smews]

I have started having issues using my Canon R5 Mark ii with the RF 600mm F4 L IS USM lens. Occasionally, it switches to manual focus mode, by itself. I.E. I do not change the lens switch or any other setting, but auto-focus stops working and the viewfinder shows manual focusing aids. Turning the camera off and on does not fix it. However, turning the focus ring does! (I don't remember changing any settings that might cause this and I do not remember it happening before the last week.) Any ideas what could be the problem, before I send them to Canon to be fixed, only to be told it is a user error?

[Waddizzle]

Your lens is capable of entering a “manual override” focus mode.  That’s all I know.

[Anonymous]

Maybe the camera looses (partial)contact with the lens, try cleaning the contacts. See if the metal rings on camera/lens are still firmly attached.

[Waddizzle]

“ Maybe the camera looses (partial)contact with the lens, try cleaning the contacts. See if the metal rings on camera/lens are still firmly attached. “

Unless you can see debris on the contacts, cleaning them rarely works.  In fact, you are likely to damage the gold plating if you are not careful.

The lens has a switch that can disable AF temporarily, putting it into a manual focus mode.’

 

[Anonymous]

'The lens has a switch that can disable AF temporarily, putting it into a manual focus mode.’

But the OP says: ' I do not change the lens switch or any other setting'  although it could be a defect in the switch. These switches are very hard to accidentally move. With heavy lenses there's more change of a bit of play/bad contacts.

[Anonymous]

Or or you talking about these buttons? This works only as long as you press the button. I own the RF400 2.8, functionally the same lens(they even share the manual) and I've never managed to accidentally press one, they are to far forward(or my arms are too short😄).

 

[Waddizzle]

Yes. The “AF Stop” button(s).

[Smews]

Those buttons are far to distant to accidentally press 😀

Also, the AF/MF switch is not easy to move accidentally, either.

I will check the contacts for anything obvious, but I have switched in/out my RF 1.4x TC a few times, so my guess is that should have resolved a contact issue.

I think the biggest clue is that it is fixed by manually altering focus. But I have no idea what that could mean.

I have plans for the next few weeks, so I will live with it and hope it does not get worse and, if it does not miraculously fix itself, it looks like it will all be on the way to Canon in the New Year to take a look!

Thanks for the suggestions.

[Anonymous]

Those buttons are far to distant to accidentally press 

Also, the AF/MF switch is not easy to move accidentally, either.

I agree, my answer was to Waddizzle.

I think the biggest clue is that it is fixed by manually altering focus. But I have no idea what that could mean.

That partly why I was thinking play/loose contact, as soon as you grab/move the focussing ring you're altering pressure on the lens and contacts.

[Smews]

Hmm. Next time it happens, I'll try to remember to just try moving the camera/lens join and see if that works. Would confirm the hypothesis and the need to go back to Canon to be fixed.