Try this: gently but firmly shake your phone near your ear. Do you hear a faint rattling or clattering sound?
If you do, there's no need to panic - you probably own a slightly more expensive phone. Cheaper models usually don't make this sound unless they're genuinely broken.
For most mid- to high-end phones, a bit of rattle is expected.
The light rattling sound usually comes from the fact that when you shake the phone, the rear camera inside the phone is moving around.
So, why does the rear camera move inside the phone?
If your phone is equipped with optical image stabilization (OIS), at least one of the rear cameras likely has a mechanical stabilizer built for the camera element itself. In such phones, the rear camera element typically has the ability to move a couple of millimeters inside the phone when that particular camera isn't in use.
This changes when the camera with optical image stabilization is activated, i.e. when you open the camera app and the zoom level corresponds to the OIS-equipped camera. At that point, small magnets around the camera sensor "grab" the camera, reducing its free movement.
In practice, the camera element floats inside the phone so it can move freely to counteract the phone's motion, reducing shake in your photos and especially in videos. Phones with OIS are typically more expensive because the mechanical solution is rather expensive to build.
The difference is particularly noticeable when filming video while walking; compare footage from a phone with OIS to one without, and you'll see a clear improvement - footage with OIS-equipped phone is much smoother.
Even in high-end phones, optical image stabilization is usually only found in the main camera and sometimes in the telephoto ("zoom camera") - but rarely, if ever, in the ultrawide camera.
Sources:
Note: Some phones implement OIS differently, so they may not rattle even when the camera is not in use. Usually, this is achieved by keeping the electromagnets that hold the camera element in place slightly active at all times.
For most mid- to high-end phones, a bit of rattle is expected.
The light rattling sound usually comes from the fact that when you shake the phone, the rear camera inside the phone is moving around.
So, why does the rear camera move inside the phone?
If your phone is equipped with optical image stabilization (OIS), at least one of the rear cameras likely has a mechanical stabilizer built for the camera element itself. In such phones, the rear camera element typically has the ability to move a couple of millimeters inside the phone when that particular camera isn't in use.
This changes when the camera with optical image stabilization is activated, i.e. when you open the camera app and the zoom level corresponds to the OIS-equipped camera. At that point, small magnets around the camera sensor "grab" the camera, reducing its free movement.
In practice, the camera element floats inside the phone so it can move freely to counteract the phone's motion, reducing shake in your photos and especially in videos. Phones with OIS are typically more expensive because the mechanical solution is rather expensive to build.
The difference is particularly noticeable when filming video while walking; compare footage from a phone with OIS to one without, and you'll see a clear improvement - footage with OIS-equipped phone is much smoother.
Even in high-end phones, optical image stabilization is usually only found in the main camera and sometimes in the telephoto ("zoom camera") - but rarely, if ever, in the ultrawide camera.
Sources:
Note: Some phones implement OIS differently, so they may not rattle even when the camera is not in use. Usually, this is achieved by keeping the electromagnets that hold the camera element in place slightly active at all times.
