It is quite common for fine particles of dust on, or in front of, the camera's internal imaging sensor to show up in the photo. They are not caused by the lens in any of the following circumstances.
- The flaws appear in the same place even when the focus or zoom is changed.
- The flaws are blurred when the photo is shot with an open aperture, but appear clearly as dots when the aperture is closed.
- The flaws do not appear when another camera is used. Or they appear in a different place.