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Wandalynn · ‎09-12-2023

I had seen in another post about a firmware update for the EF 100-400mm f/4.5-5.6L IS II USM (which I discovered the previous 1.0.6 version on mine). I hope this isn't a dumb question but can I do the update via an RF to EF adapter on my R5 or R6ii?

Anonymous · ‎09-12-2023

I would think that if it is a Canon adaptor, you should be good to go. If you did the download of the firmware update file, it has instructions included.

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shadowsports · ‎09-12-2023

Greetings,

I agree with Bob. If the current FW for the lens displays in the R5's menus, you should be able to apply the upgrade. Please put the "EF008107.lfu" file on the root of a freshly formatted (in camera) SD card. If you have a CF Express card installed, remove it temporarily prior to performing the upgrade. You will also want to use a fully charged battery.

While the behavior that v1.0.7 addresses is rare, I'd install it to be safe.

~Rick
Bay Area - CA

~R5 C (1.0.9.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It

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shadowsports · ‎09-17-2023

Excellent. I did 3 lenses last night and actually reviewed the update procedure. It does change depending on your hardware. I noted this. ➡️ OK to use supported mirrorless body to upgrade EF glass with EF to R adapter.

~Rick
Bay Area - CA

~R5 C (1.0.9.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It

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Question about Firmware Update to EF 100-400mm f/4.5-5.6L IS II USM