Share your experience!
Do you have a back case or screen protector?
Maybe you could take it off and try like that?
Do you also have a screen protector on the back of the device? You could try settings-apps-all-camera,force stop and clear data too.
Could you take a look at the camera lens for any scratches? Maybe it would be wise to take your device to a sony service:
http://www.sonymobile.com/global-en/support/contact-us/
You should have the device examined.