Sorry for the late reply, I should really check on my itch account more often.
To find the Camera Effect you need to go to the Vaporwave World by using the Eye Triangle. Once there go down a bit and you should see 2 rows of Cans that create a pathway between them. Go down through the tunnel and you'll be in the Neon City. Once there you'll have to find 12 of these Neon Creatures. An important thing to note is that there are some invisible pathways you'll need to traverse. There's aren't too complicated and are noted by slight holes in the green tiles, that indicate there entrances. Each Neon Creature removes a block from a path in the lower left part of the city. Once you get all 12 you can use the path, find a box and collect the Camera Effect.
In retrospect I shouldn't have made finding the Camera Effect so hard considering it's needed to unlock wallpapers. I'm glad you liked my little fan game enough to want to 100% it! Best of luck!