Here is the full list of all 46 Viewfinder achievements. It takes around 5-6 hours to unlock all of the achievements on Windows.
Collect all the camera filters
Find all the planets in chapter 4
Complete the game
Complete the simulation shutdown sequence
Break the windmill inside the painting
Go for a walk in the barcode forest
Ride the train to the final hub world
Complete the picture frame levels in chapter 4
Complete all the optional challenge levels
Draw using the green pencil
Make a choir of screaming people
Take 100 Photos
Complete the illusion levels in chapter 3
Get behind the waterfall
Find all the mahjong tiles in chapter 3
Ride a balloon
Complete a timer level with only a fraction of a second to spare
Beat a level in less than 10 seconds!
Slice a Dustin
Make an army of Dustins
Drop a Dustin off the level
Get multiple jump powerups
Get the jump powerup
Break the cartoon rope bridge
Make the maximum possible number of batteries in the first camera level
Find all the magnets in chapter 2
Get tricked twice in a certain level
Carve the melon repeatedly
Put the three paintings where they belong
Place the recursive photo 15 times
Rewind for a really long time
Drop a battery onto your head
Find all the ducks in chapter 1
Complete the third level without touching the battery
Release all the blueprint Dustins
Place a photo while falling and land on it
Take 25 photos
Try duplicating Cait
Get the camera
Drop a battery off the level
Grow the flower to attract a bee
Put down both playing cards
Pet Cait
Ride the train
Return to the hub world
Break the only teleporter