Canon has identified a fault that can occur in some early versions of mass-manufactured EF24-105mm f/4L IS USM lenses.

The fault occurs in the form of shower-like ghosts, or flares. The flare will not appear under normal shooting conditions, so the lenses can be used without trouble in most circumstances. However, under limited conditions (such as backlit or night scene shots where a strong light source shines from behind the shooting object), a flare may appear. In those instances, users can avoid the effect by slightly changing the camera's direction or focal length (angle of view) while checking for flares through the viewfinder.

To determine if your lens is affected, please check the control number of the product. Canon will repair affected products free of charge, and apologises for any inconvenience this may have caused.

Affected model and control numbers: EF24-105mm f/4.0L IS USM The control number is indicated on the back cover of the lens (see the example shown in the red ellipse on the right). If it contains the lettersUT followed by a number under 1,000, the product may be affected. Should you have any difficulty identifying the control number, please contact Canon's Customer Service helpdesk.