Ok the "noise" I am talking about here is not noise in photos, it's actual small noise/sound coming from camera.

I have been using my camera for around 6 months, but never noticed this before. May be because I have been with people/outside. Last week I was sitting alone at home, and focusing on an object when I noticed small noise from sensor. The noise comes only when I half press the shutter button to auto focus, and stops as soon as I take off my fingers from button. The noise is like a computer fan..but not that loud of course. Should I assume this to be normal?

  • \$\begingroup\$ Are you sure the sound is coming from the sensor? \$\endgroup\$
    – mattdm
    Feb 14, 2012 at 19:34
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    \$\begingroup\$ I changed "noise" to "sound" in your question title as I think it would confuse people searching for questions on sensor noise. \$\endgroup\$
    – MikeW
    Feb 14, 2012 at 19:38
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    \$\begingroup\$ Following up on what @mattdm asked, there is a focus motor in the Canon lenses that is activated to move the focus elements when the autofocus is triggered -- typically pressing the shutter release halfway. Also, the IS motor often activates at that point. What lens do you have and does it have the IS and/or USM designator? \$\endgroup\$
    – Steve Ross
    Feb 14, 2012 at 19:39

2 Answers 2


The only sound that would come from the sensor itself would be a self-cleaning function, which only happens when you run the self cleaning, or turn the camera on/off. The sensor vibrates to shake off dust. This would not be happening when you are shooting.

When you half press, the sounds you might hear would be from the lens AF motor or image stabilisation (IS). Try putting the lens in manual focus and turn off IS if your lens has it, and see if you still hear a sound.


I checked on my 550D (good thing I'm alone in the room, I must have looked like an idiot with the camera on my ear) and a sound like what you described comes from the lens image stabilization.

If I turn IS off, use a lens without IS or with no lens attached the camera is completely quiet (except for the AF motor, obviously)


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