Applications not installed during backup
iPhone hanging or running slow
Wi-Fi signal / connectivity issues
Battery draining very fast or iPhone heating up
Microphone not working Properly
iPhone does not Turn on
What if IPhone is lost / stolen
Courtesy : Apple support Forum
Best possible solution is to go to Apple support Forum.
After switching on camera, Long press inside screen, you will get the option of AE/AF lock. A useful tool for focus.