R series self adjusting iris behavior normal or fault?

[Zshuterbug]

I just mounted a Tamron 90mm macro lens on my R100 using the genuine Canon EF adapter, A mode. As I am walking around outside I noticed a noise from the lens. Looking from the front I see the iris opening and closing as i point the camera toward dark shadow and then to bright light. I am not changing anything in the camera settings, Hmmm. I put the kit lens back on and try the same motion. The kit lens does the same iris open and close, but it is so silent that I have never noticed this before. Tried with many EF lenses and they all do this, its just on noisy lenses that it is noticeable. Camera does this in every mode including Manual. Exposure simulation, auto iso, manual focus settings seem to have no effect on this behavior. When the ambient light changes significantly, the iris compensates. All photos come out exposed perfectly.

Can anyone confirm this behavior and explain it?

Thanks

 

[Leigh A]

If you have Continuous Focus enabled, along with Aperture Priority I suppose that could happen?

 

[John Sheehy]

I just mounted a Tamron 90mm macro lens on my R100 using the genuine Canon EF adapter, A mode. As I am walking around outside I noticed a noise from the lens. Looking from the front I see the iris opening and closing as i point the camera toward dark shadow and then to bright light. I am not changing anything in the camera settings, Hmmm. I put the kit lens back on and try the same motion. The kit lens does the same iris open and close, but it is so silent that I have never noticed this before. Tried with many EF lenses and they all do this, its just on noisy lenses that it is noticeable. Camera does this in every mode including Manual. Exposure simulation, auto iso, manual focus settings seem to have no effect on this behavior. When the ambient light changes significantly, the iris compensates. All photos come out exposed perfectly.

Can anyone confirm this behavior and explain it?

This is normal behavior.

When the camera is doing live view, it may stop down faster lenses, maybe to optimize the exposure of the c-log video used in live view.

IOW, the camera may be using something like ISO 800 for live view, and wide-open fast lenses may be too bright for the camera's preferences. My R7 allows you to force the exposure-time f-number during live view (accurate DOF), so it is not impossible to use a fast f-number, but maybe it forces a faster shutter speed in live view than what the system would prefer.

 

[Sittatunga]

This behaviour also happens with my M100 and my Samyang 35mm f/1.4 (the version with contacts and no aperture ring). I guess (English English guess, i.e. a wild hypothesis) it could be something to top with keeping the light intensity within a comfortable range for the DPAF. I'd say it's normal.

 

[Andy01]

If you have Continuous Focus enabled, along with Aperture Priority I suppose that could happen?

I think this is a likely cause, except that OP mentioned full Auto mode, not Av, which is probably worse, because not only would the camera be trying to focus continually, but may be continually changing the aperture, shutter speed and possibly ISO settings as well.

I don't know for sure because I never use either continuous AF or full Auto settings.

 

[Zshuterbug]

If you have Continuous Focus enabled, along with Aperture Priority I suppose that could happen?

I think this is a likely cause, except that OP mentioned full Auto mode, not Av, which is probably worse, because not only would the camera be trying to focus continually, but may be continually changing the aperture, shutter speed and possibly ISO settings as well.

I don't know for sure because I never use either continuous AF or full Auto settings.

To clarify;

Focus servo and Continuous focus did not affect the iris self operation. They did add to the noise on noisy lenses. Other than that I could not find any modes when this phenomenon did not occur. I did come across some threads where the poster wished for capability to turn off live view on R series. If available it would probably stop the auto adjustments.

The noise is so bad on the Tamron Macro 90mm that I worry about the extra wear on the blades. As long as you dont swing the camera between the sky and the earth the action can be minimized. You can also tell that the camera is "trying" to maintain a constant iris opening by slowly moving the lens from pointing at a dark surface toward the sky. It stayes open until the last moment, and then it closes down.

PS as a test I tried the same lens on an older 7D, and the iris stayed put in wide open in all the modes until the shutter was half pressed. Goes along with the theory that the open/close action is to maintain sensor/screen sensitivity in a sweet spot, which is not needed (except live view) in a optical view finder camera.

 

[Andy01]

I did come across some threads where the poster wished for capability to turn off live view on R series.

I wasn't aware that "Live View" could be turned off on any mirrorless camera.

The noise is so bad on the Tamron Macro 90mm that I worry about the extra wear on the blades.

Does this lens perhaps need a firmware update to function properly with a newer R body ?

Have you tried a different lens on the R body to see if it does the same thing ? When it comes to Canon R bodies and third party lenses, some odd things tend to happen with some of them, especially older lenses or MF lenses with electronic aperture.

As long as you dont swing the camera between the sky and the earth the action can be minimized. You can also tell that the camera is "trying" to maintain a constant iris opening by slowly moving the lens from pointing at a dark surface toward the sky. It stayes open until the last moment, and then it closes down.

PS as a test I tried the same lens on an older 7D, and the iris stayed put in wide open in all the modes until the shutter was half pressed. Goes along with the theory that the open/close action is to maintain sensor/screen sensitivity in a sweet spot, which is not needed (except live view) in a optical view finder camera.

Have you tried using Av (aperture priority) mode instead of full Auto ?

 

[Leigh A]

I did come across some threads where the poster wished for capability to turn off live view on R series.

I wasn't aware that "Live View" could be turned off on any mirrorless camera.

That was/is my impression as well. Live View is a term where on DSLR's the mirror was lifted out of way, and a "live view of the scene off the sensor could be displayed on the LCD.

I thought that on mirrorless cameras the image view on the sensor could be displayed either on the EVF, the LCD, or both any time the camera is "awake", Am I wrong?

 

[R2D2]

I just mounted a Tamron 90mm macro lens on my R100 using the genuine Canon EF adapter, A mode. As I am walking around outside I noticed a noise from the lens. Looking from the front I see the iris opening and closing as i point the camera toward dark shadow and then to bright light. I am not changing anything in the camera settings, Hmmm. I put the kit lens back on and try the same motion. The kit lens does the same iris open and close, but it is so silent that I have never noticed this before. Tried with many EF lenses and they all do this, its just on noisy lenses that it is noticeable. Camera does this in every mode including Manual. Exposure simulation, auto iso, manual focus settings seem to have no effect on this behavior. When the ambient light changes significantly, the iris compensates. All photos come out exposed perfectly.

Can anyone confirm this behavior and explain it?

This is normal behavior.

When the camera is doing live view, it may stop down faster lenses, maybe to optimize the exposure of the c-log video used in live view.

IOW, the camera may be using something like ISO 800 for live view, and wide-open fast lenses may be too bright for the camera's preferences. My R7 allows you to force the exposure-time f-number during live view (accurate DOF), so it is not impossible to use a fast f-number, but maybe it forces a faster shutter speed in live view than what the system would prefer.

+1 folks. The camera is doing exactly what it was programmed to do.

If there are concerns about the lens or the noise, you'll just have to get a different one.

R2

 

[Leigh A]

This is normal behavior.

When the camera is doing live view, it may stop down faster lenses, maybe to optimize the exposure of the c-log video used in live view.

+1 folks. The camera is doing exactly what it was programmed to do.

If there are concerns about the lens or the noise, you'll just have to get a different one.

R2

I was under the impression, perhaps wrongly so, that C-Log was a Video Mode function?

 

[John Sheehy]

I was under the impression, perhaps wrongly so, that C-Log was a Video Mode function?

Yes. What do you think live view is? It is video.