When a photographer picks up a camera to shoot a scene he sees in his mind's eye, is he merely documenting the scene unfold in front of him? When a photographer crop out an element or two within a scene, is her photograph merely an illusion to the reality? How can we even distinguish between illusion and reality? My answer is "we can't", because there are just way too many factors in play when we view a photograph.
I think all photographs are illusion in some way or another, even when we label them as "documentary". With all different kinds of portrait genre out on the photography world today, can we even distinguish the differences between lifestyle, documentary, environmental portraits, honest photography, yada yada yada? A lifestyle portrait can be staged, a documentary can be cropped and altered, and I don't even understand what "honest photography" really means! I think it is simply pointless to draw a definitive line to define these genres.
A photograph, as with any art, not only depends on the viewer's perception, it is also built upon how the photographer sees the scenes and how he frames it so the viewers can see what he sees...well, sort of. A photographer can simply include or exclude a definitive elements within her frame to completely change the content and viewers' interpretation.
I believe whether you are a documentary or a portrait photographer, you are given the liberty to alter and mold the reality into an ideal photograph by using light and other elements. It's like when Michelangelo painted the ceiling of the Sistine Chapel in the 16th century, we have no idea what Michelangelo thought when he painted it. When we look at it today, we can only see it with our limited perception. A person who is not familiar with the Bible stories will have absolutely no idea what these paintings mean.
What do YOU think? Do you think all photographs are illusion on some level?