This achievement is earned for finding optional photo #5. If missed on the first run, you can "Play Episodes" and select specific parts of the Episode in order to find the missing optional photos through collectibles mode. The following collectible is described and can be seen below:
] - Optional Photo #5
Directly behind the whale in photo #4, near the diner, take a picture of the car on the roof of the nearby house. Make sure you angle the photo from the alley.
Collecting all 10 photos will also reward you with the following achievement: