I have the same problem, try turning off your device,press the low volume button and power button at the same time, when you see the logo appear release the power button,but continue to press the low volume button. When your home screen appears you should be in safe mode,try your camera then,if it works then you have a third-party application that is causing the problem. I'm working on finding out which app is causing this problem on my tab4. I hope this is helpful for you.