... you take multiple shots of a subject and don't like any of them.
... you feel panicky when someone hands you a compact camera and you can't control the exposure.
... you get arthritis in your trigger finger.
... when you're balanced precariously on a high ledge, you're more worried about dropping your camera than falling to your death.
... you understand the meaning of ISO and SLR.
... you have a camera strap tan/rash.
... you can live without bringing your phone on a trip, but not your camera gear.
... you start seeing life in bokeh.
... your camera goes in to the shop for repair and you feel like your pet just died.
... you're willing to get up at 5 am to go and photograph the sunrise.
... you wish your eyes had an inbuilt camera for days when you're not carrying the camera.
... you have to sort through the hundreds of pictures you take during a trip - none of which you are in.
... your world is a blur, but the subjects around you are in focus.
... you do an awkward pose in public to get the best shot.
... you buy magazines for the photos and not for the text.
For more check out the You know you're a photographer when website.