topic Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF in EOS DSLR & Mirrorless Cameras

EOS R5 Mark II with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Sun, 06 Apr 2025 12:32:48 GMT

Camera: R5 Mark II ( Camera Firmware Ver 1.0.2)
Lens: RF 100 - 400mm F5.6 - 8 IS USM (Lens Firmware Ver 1.0.3)

Every now and then, this Camera/Lens combination fails to achieve AF.

I'm using AF-ON back button with the following settings:
AF start position : Manual selection
AF operation : SERVO
AF Area : Around
Whole area tracking servo AF : ON
Subject to detect : Animal
Eye detection : AUTO
Servo AF characteristics : M

I can't say for sure, but it may be getting in to this situation after the camera goes through an auto power off (not consistently)

One way I have been able correct this situation is by turning the camera OFF and ON.

Anyone has experienced this? Any suggestions on how I can prevent this from happening.

Thanks.

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Sat, 05 Apr 2025 14:46:01 GMT

Added Info: Most of the time the camera achieves AF with no issues. I haven't tested this scenario with other RF lenses

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

deebatman316 — Sat, 05 Apr 2025 14:52:22 GMT

Check and see if "Lens Drive when AF is Impossible" is Enabled in the camera menu. If not the camera will give up and stop trying focus.

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

Waddizzle — Sat, 05 Apr 2025 14:59:26 GMT

Welcome to the community. We are going to need a lot more information about your issue in order to help you. Please, tell us how to reproduce the issue.

Photos or videos?

What are you trying to focus on? Is it moving?

How far away is the subject? Does the subject fill the frame?

Describe the lighting conditions.

That’s a good start. I’ll stop here. Feel free to add any additional information that you feel could be relevant and helpful.

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Sun, 06 Apr 2025 13:37:27 GMT

Thank you. I checked and the setting was set to OFF. I just changed it to ON.

Since the issue only happens sporadically, I can't readily test if this setting change fixed it. I will let you know if it ever happens again now that I have changed the setting.

Thank you.

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Sun, 06 Apr 2025 13:51:00 GMT

As I mentioned, unfortunately this issue is not reproducible at will.

I'm using in Photo mode.
It doesn't seem to matter what I'm trying to focus on. I have been trying on objects with plenty of contrast.
When if happens, the distance to the subject also doesn't seem to matter.
It has happened in bright lit situations.

Thanks.

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

Waddizzle — Sun, 06 Apr 2025 15:19:18 GMT

Iwatawala, thanks for your responses.

” Every now and then, this Camera/Lens combination fails to achieve AF.

I'm using AF-ON back button with the following settings:
AF start position : Manual selection
AF operation : SERVO
AF Area : Around
Whole area tracking servo AF : ON
Subject to detect : Animal
Eye detection : AUTO
Servo AF characteristics : M

I can't say for sure, but it may be getting in to this situation after the camera goes through an auto power off (not consistently) “

I would beg to differ with your opinion that the issue cannot be easily or effectively reproduced. The devil is in the details.

Where is the setting highlighted in bold located and what does it do?

It isn’t clear from your replies just what it is that you are trying to focus on and how well it fits or fills the viewfinder. Is your subject moving?

I noticed that your settings suggest that you could be trying to focus on wildlife. Let’s change them to see if you have a camera problem or a shooting conditions problem.

As a test, I suggest disabling Eye and Subject Detection. It is possible that the camera is getting confused with whatever it is you are trying to focus on.

One common shooting scenario that can confuse the camera is a small bird sitting on a tree branch. Nearby branches can get in the way, even if you have a clear line of sight to the bird.

A hummingbird hovering near a feeder can cause problems because they can move around so quickly.

Repeating the complaint that it doesn’t work doesn’t help someone to help you.

Re: EOS R5 Mark II with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

shadowsports — Sun, 06 Apr 2025 15:41:38 GMT

Greetings,

Excellent you have enabled lens drive when AF is not possible as deebatman316 suggested.

Waddizzle has also provided helpful information and given you some settings and further recommendations that might help you consistently reproduce the behavior. I don't think I've had any instances where my RF 100-400 has failed to acquire focus. I use one spot AF 95% of the time. I'm sure your AF is slightly more advanced than mine. I don't use BBF and consistently get fast, accurate results using the shutter button half press. I do use the AF on button occasionally. One other suggestion, save your existing settings to an SD card. Then reset the camera and put it through a battery of testing to see if the behavior persists. It may take a bit of work on your part, but eventually you might be able to figure it out or at least get to the point where you are aware of when the challenge/behavior might happen.

Re: EOS R5 Mark II with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

Waddizzle — Sun, 06 Apr 2025 15:54:06 GMT

One alternative to resetting the camera is to switch the shooting mode to Intelligent Auto, Green [A+], instead.

Re: EOS R5 Mark II with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Mon, 07 Apr 2025 08:28:35 GMT

Thank you All for your responses. To answer your questions:

When this situation occurs, it doesn't seem to matter what I try to focus on (a bird, a dog, a tree, a building etc), pressing AF-ON button just doesn't achieve focus. As I mentioned in my earlier reply, I have now enabled the "Lens Drive when AF is Impossible" and continuing to test. Unfortunately, this situation was not readily reproducible. So, I will just keep testing and I'll let you know if it ever happens again with this setting enabled.

As for " Servo AF characteristics : M", it is the parameter you set in Menu option AF.3 (Purple 3). That parameter is available during detail customization of the AF-ON button by pressing INFO

Hope this is all clear.

Re: EOS R5 Mark II with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

Waddizzle — Mon, 07 Apr 2025 16:51:17 GMT

Thanks again, for your replies.

When you press the [AF-ON] button, do you keep it pressed until you complete the shot?

Re: R5 Mark ii with lens RF100-400mm F5.6-8 IS USM - Every now and then fails to achieve AF

lwatawala — Thu, 22 May 2025 22:00:19 GMT

I have used the camera with "Lens Drive when AF is Impossible" Enabled for some time now and haven't seen the issue I encountered with focusing. So, I have accepted this as the solution.

Thank you everyone for your input and suggestions.