Thre's a camera icon to the right of your "slide to unlock." Up to 5.0.1 you tap it... 5.1 & 5.1.1 you slide the icon up onto the screen to open the camera.
On 5.0.1 you need to double click the home button when it's locked. 5.1.1 has the camera shortcut beside the slide to unlock
Ahhhh yes... thank you for clarifying that. Been a while since I was on 5.0.1 and didn't remember the double click. Thanks!!