RF 100-400mm f/5.6-8 IS USM - Focus ring not responding

[Fabri91]

I recently purchased a RF 100-400 mm lens, to be used with my EOS R8.

The lens seems to be working fine, but it's the first one that I have that has a separate focus ring and control ring, and I suspect that there may be an issue with the focus ring.

Specifically:

• Autofocus seems to work fin
• When selecting MF on the lens the camera correctly detects this change in setting
• When in MF mode the focus ring does not seem to do anything

Am I missing anything to be able to manually focus? Using the kit lens (24 - 50 mm) this seems to work fine - since that lens only has a single ring, I also have to select the function "Focus" instead of "Control" on the lens itself, as expected, in addition to selecting "MF". The lens then reacts to the ring commands.

Is there any way (a diagnostic function, perhaps) in which I could specifically verify that the focus ring encoder is working?

Thanks!

[deebatman316]

Is the camera set to One Shot? If not the electronic focus ring is ignored. This restriction has been in place since 1987. With the release of the first Ring Type USM lens.

[Waddizzle]

Make certain that the metering system is active.  

[FloridaDrafter]

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@deebatman316 wrote:

Is the camera set to One Shot? If not the electronic focus ring is ignored. This restriction has been in place since 1987. With the release of the first Ring Type USM lens.

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Hello, Demetrius!

I can't speak for the R8, but with my R6 II, MFO works in whatever mode you are in while using the RF 100-400 in particular, i.e. servo, whole area, eye tracking, animal, etc. On top of that, when all of your MF criteria is set and you use the MF ring to override AF, half press or not, AF features start to kick in along with MF when you start to get a subject in focus. For example, if I have the Focus guide on and I start to get my subject in focus using the guide, eye and subject tracking activate and will highlight the subject or it's eye while using the MF ring. I haven't tested this on my other  R's and RF lenses because I seldom if ever use MFO. The R6 II and RF 100-400 are my wife's, and although I am thoroughly familiar with it [R6 II], it doesn't get a lot of my attention except to help folks troubleshoot 🙂

IIRC, the R8 shares most of the abilities of the R6 II, so it should act the same in most respects. But there has to be certain "enticements" to get people to spend another $1,000 for the next camera up the line, LOL!

Newton

[deebatman316]

On DSLRs in live view the electronic focus ring always works unless it’s set to Servo AF.

[FloridaDrafter]

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@deebatman316 wrote:

On DSLRs in live view the electronic focus ring always works unless it’s set to Servo AF.

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True, but we are talking about MILC's, and from my perspective, this particular lens on my R6 II 🙂

I need to test all my other MILC's and RF glass to see if they behave the same.

Newton

[deebatman316]

Adapted EF lenses on RF Mount cameras also ignore the focus ring when the camera is set to Servo AF or AI Focus. I've also heard it was by design to ignore it because you'd be fighting the AF system when set to Servo AF or AI Focus. But not One Shot because it has focus lock which doesn't happen in Servo AF.