Sigma are offering a free upgrade service to Canon EOS 40D users experiencing problems with the 120-400mm and 150-500mm lenses. When the Canon 40D digital SLR is in AI Servo AF mode and the OS function is switched ON, the number of continuous frames per second will decrease. This issue affects all Sigma APO 120-400mm lenses with a Serial Number lower than 1011001, and all Sigma APO 150-500mm lenses with a Serial Number lower than 1007001.

Sigma Press Release

Notice to Canon 40D owners using Sigma’s APO 120-400mm F4.5-5.6 DG OS HSM or APO 150-500mm F5-6.3 DG OS HSM for Canon fitting

2008.5.27

When the Canon 40D digital SLR is in AI Servo AF mode, and the APO 120-400mm F4.5-5.6 DG OS HSM for Canon or APO 150-500mm F5-6.3 DG OS HSM for Canon lenses are attached to the camera with the OS function switched ON, the number of continuous frames per second will decrease.

To overcome this, we will start supplying a free-upgrade service to our customers from today.

We deeply apologize for any inconvenience this may have caused to our customers.

List of lenses requiring update for 40D camera
APO 120-400mm F4.5-5.6 DG OS HSM for Canon Serial Number lower than 1011001
APO 150-500mm F5-6.3 DG OS HSM for Canon Serial Number lower than 1007001

Except above numbers, their firmware has already been updated.

For further information, please contact your nearest authorized Sigma Service Station.
http://www.sigma-photo.co.jp/english/network/index.htm

Your Comments