Expert: Abe - 1/3/2008

Question
Hallo Abe,

I have sigma 70-300mm f4-5.6 APO Macro. Previously it is used on my Canon EOS D30 (not 30D) and worked excellent. Now, I have EOS digital rebel Xti. I tried to use the sigma lens on my rebel xti but it showed error 99 on the screen. It asked to turn OFF and ON the camera or reinstall the battery. I did it but it still showed error. What happened to my camera? Thank you very much.

regards,
Ben

Answer
Hi Ben,

Canon does not guarantee that any non-Canon branded lens will be compatible with their products. The Sigma may have been developed around the time of the D30, but by the time the XTi came out, some  of the electronics may have changed and the Sigma lens may not have been updated to match it. Sometimes, 3rd party lens makers will "re-chip" a lens to make it compatible with current camera models. You might want to ask Sigma about that.

But the problem may not be one of compatibility. The error99 on your screen may have to do with dirty contacts on the lens. It is recommended that you take a clean pencil eraser and rub the gold contacts on both the camera and lens. I have used this method with success in the past. I would try this first before contacting Sigma about a lens re-chip.  

Please let me know if either of these suggestions works.

All the best,
Abe