Hedgehog in the Fog, 1975
Considered to be one of the greatest animators masterpiece by the Russian animator Yuri Norstein is multi plane stop motion animation with replacement cell drawing of a hedgehog lost in the forest. No special effect was used to make this enchanting piece.
I attached a video of Norstein giving talks about how he made his animation and he used translucent papers to create the fog with the camera depth of field. His wife Francheska Yarbusova, doesn't get enough credit for making all the painted pieces used in making his films.