This is one of the most coolest of the lumia tricks I know. When you open the camera button through the dedicated camera key, or through the apps in the UI of the phone.
The lenses modify and customize the camera capabilities to a great extent. Whether it be the Cinemagraph ir the Nokia City Lens, they really customize your pictures by animating them and City Lens is really helpful for finding certain locations and nearby place you visit. So these gestures make into the coolest lumia tricks.