Share your experience!
I've seen this before if the camera lens its scratched or dirty, or if there's something near or on the lens.
Settings > apps > all > camera > clear data > restart the phone
if that doesn't work then repair the phone with PCC
Bridge (for Mac)
Alternatives on How to backup Xperias
http://talk.sonymobile.com/thread/36355
if that doesn't work then contact your local Xperia Care as it could be a hardware issue Local support