Auto Focus not locking on 5d mark ii

[Oystersk]

Hi

I have had my canon 5d mark ii for 3 years and has been working fine but have just noticed that when press the shutter button half way to focus and move the camera to recompose the point the camera is focusing move too.  The only thing I can thing of is that I updated the firmware from the orginal factory setting to v2.1.2 about a month ago, I have only noticed as have taken some wide aperture shots and the focus is not where I locked it, I have played since and the focus never holds.  I have browsed through the menu and can't see anything to upset the focus locking, does anybody know what I need to do?

Thanks

Sarah

[ebiggs1]

One Shot or AI Servo?  Check that.  It needs to be on One Shot.

[Oystersk]

I am using one shot, it used to hold, I have had this camera for 3 years and it is something new. It focuses perfectly if I don't move the camera after focusing.

[cale_kat]

It might be a problem with the lens. Have you tried cleaning the contacts?

[Oystersk]

Good plan, I will have a go it might be connected as I got a new 50mm prime lens last week, it makes more sense than me not noticing the problem for a month since I updated the firmware.