Check the focus mode switch on the lens
Autofocus will not operate if the focus mode switch on the lens is set to <MF>.
Set the focus mode switch on the lens to <AF>, as shown in the image below.
Clean the lens and camera electrical contacts
The transfer of information between the camera and the lens is carried out by the electrical contacts on both the camera and the lens.
If the contacts on either the lens side or the camera side get dirty, communication cannot be carried out correctly, and in some cases the autofocus may not operate correctly. If the lens or camera contacts get dirty, please clean them very gently with a clean, dry cloth.
Precautions on cleaning contacts:
- Do not wipe the contacts with a wet cloth. It could cause malfunctions.
- Do not touch the contacts directly with your hands. Touching them with your hands could cause corrosion, which would cause the camera to become inoperable.
- When cleaning the contacts on the lens side, be careful not to damage the lens surface.
- If the contacts are particularly dirty, please contact the nearest Canon Service Center.
Securely mounting the lens
Both the camera and the lens mutually exchange information. For this reason, if the lens is not securely mounted, there may be cases where the autofocus does not operate correctly.
Please mount the lens securely, as shown in the image below.
Check the custom function setting for [C.Fn-9: Shutter/AE lock button]
If the autofocus does not operate when you half-press the shutter button, it might be because the setting for the [C.Fn-9] custom function has been changed to 1.
In that case, the setting is set to use AE lock (which fixes the exposure) when the shutter button is half-pressed, so change the setting to 0. Please see the Instruction Manual that came with your camera for details about how to change the setting.
If you have checked all of the items listed above, but there is still no improvement, please contact the nearest Canon Service Center.
Note that, if you are experiencing trouble with a lens made by another manufacturer, you should contact manufacturer of that lens instead.