Canon has issued a firmware update for the EF 40mm f/2.8 STM lens.
Firmware Version 1.2.0 addresses the following phenomenon.
1. If pressure is applied to the lens barrel while the lens is mounted to the camera (pressure can be applied even while attaching the lens cap or while carrying the camera with the lens attached in a bag), the autofocusing function of the lens may stop working.
Note that only the following cameras can be used to install the update:
- Canon 1D X
- Canon 5D Mark III
- Canon Rebel T4i / 650D
If you do not have one of these cameras, you can send the lens into a Canon service center to have the update applied. Canon USA customers can contact the Canon Customer Support Center at 1-800-652-2666.
You can download the update via Canon’s website.