Shouldn't the lens stabilizer motor humming noise go silent after I flip stabilizer switch to OFF?

[blouse]

Camera: EOS R8
Lens: RF24–105mm F4-7.1 IS STM

When the camera is on, if I put my ear to the lens, I can hear the stabilizer motor humming. If I flip the stabilizer switch to OFF, I expect to hear it go silent, but it's still humming. Why?

(the stabilizer effect does turn off, tested by shooting videos)

(my old EF lens does go silent immediately after flipping the switch, tested on the same camera body, using the RF mount adapter ring)

[Waddizzle]

Beside hearing noises, what leads you to the conclusion that IS is the problem.  The default setting for the mirrorless cameras is for AF to always be active.  

Depending on camera model, the setting to disable it goes under different names.  Brian described it as “Preview AF” for the R8.  Have you checked that setting or disabled it?

[blouse]

Yes, in my reply to Brian, I mentioned (1) my Preview AF is off (2) the IS stabilizer is a different sound from the AF. When AF is not active, you can hear the constant stabilizer motor humming. When AF is in progress, you can hear both the stabilizer and the AF.

If you're not sure what on earth I'm talking about, all you need to do is put your ear on your lens body to hear the stabilizer, you can't miss it.

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@Waddizzle wrote:

what leads you to the conclusion that IS is the problem.

When I connect my old EF lens to the same camera body (using mount adapter), I can switch the stabilizer noise ON and OFF by flipping the switch. When I use this new RF lens, however, it's the exact same stabilizer noise, but it doesn't go silent when I flip the switch OFF, which makes me wonder why it doesn't.

[deebatman316]

Are you 100% sure you're actually hearing the IS motors. Some lenses have floating elements in them. They will produce noise when the camera is off or the lens is unmounted.

[blouse]

Yes I'm sure because when I turn off the camera, the sound goes away. When I turn on the camera, the sound comes back. 

It also sounds exactly the same as my other EF lens, except the EF noise does go silent when I flip the IS switch, whereas this RF lens doesn't.

I think either I got a defective RF lens, or all RF lens are like this, which isn't good because it's a battery drain.

[deebatman316]

With mirrorless the AF motor and IS are ON all the time. I used to own an older EF lens (EF 28-135mm F/3.5-5.6 IS USM lens) and when I mounted it and it clicked into place. You could hear the IS motors start up for a second then stop. I thought that was odd but Canon said it was normal. Are you using a tripod or any other stabilization device. Or are you shooting handheld. If handheld you'll need IS or camera shake will be visible in the picture. My EF 70-200mm F/2.8L IS III USM lens acts in a similar way to your RF lens when adapted to an RF Mount camera. The IS motors stop when the IS switch is set to off. The lens still makes noise but you can tell in live view that IS is turned off. Because you can see a shaky image on the LCD screen when digital zoom is used. I tested on an R6 classic, R6 Mark II, R5 & R7. I believe what you're hearing is normal and the same lens acts the same way on a DSLR camera too.

[p4pictures]

Is it possible that it's not the IS, but the aperture assembly you hear. In the RF lenses the aperture is closed when power is removed, and must be driven to the open position for AF and metering. The aperture only closes when the exposure is made or depth of field preview is pressed.

I don't have the EOS R8 or RF 24-105mm F4-7.1 IS STM lens myself, but when I just checked my EOS R10 with RF-S 18-150mm f/3.5-6.3 IS STM and held the lens to my ear I can hear a drive unit running when the camera is powered on. If I change the IS status from on to off  the same sound is heard from the lens, making me believe it is not the Image Stabiliser unit that I was hearing. Pressing the shutter button to initiate focus introduces another different sound, so I don't think the sound was an AF motor. Ultimately this leaves the aperture assembly as the possible source of the noise.

I then tried with the RF 28-70mm F2L USM lens fitted to the EOS R10. This has no lens IS. When fitted and the camera switched on there is some noise but it's not as loud as the RF-S 18-150mm lens. 

[deebatman316]

My EF lenses make a similar sound on RF Mount cameras. I think its the aperture motor. Even with EF lenses mounted the lens stops down to the smallest aperture when the camera is powered off. But it goes back to wide open when the camera is powered on.

[blouse]

Thanks Brian, you mentioned that you tried a lens without IS which produced a noise but was less loud. Was it a constant droning noise or a one-off sound when turning on the camera?

[p4pictures]

There was some kind of continuous noise from the lens without IS, but it was not as loud as the noise from the RF-S 18-150mm. The difference in sounds could also be that the RF-S 18-150mm and your RF 24-105mm use STM focus motors where the RF 28-70mm F2L has a USM focus motor. 

[FloridaDrafter]

My understanding of that "humming" is that in the R/RF system both ILS and IBIS use electromagnets to move the IS elements in order to stabilize the image. When IS is switched off, the elements in the lens (or body) still need to be held in place, so the electronics stay active/energized and that is what you hear even though IS is switched off.

Now, I have an RF 50mm f/1.2L USM (non IS) that hums, but I assume the same "active" situation is going on with the AF feature in that lens. It's way louder than any of my other five RF lenses that have AF IS. It's not something you would notice unless you press your ear to it, but it is noticeably louder.

My conclusion is that this is all normal.

Newton