When I sketch a person's gesture and study the angles and shapes, I'm seeking a kind of truth through focussed seeing. I'm trying to put aside my mental aberrations, my preconceptions of head, arm, leg. In that sense you could say photography is all truth — it comes with no preconceptions due to its mechanical nature. In fact it can tell you a lot about a person, though only in a technical way, because of how it operates.
At the same time, I believe there's a broad awareness in society that photographs also contain very little truth. They capture surface impressions, a 'snapshot' moment in time, infinitesimally small. The angle is also chosen, along with focus, lighting, in a way that limits what you can get out of it. So the photograph says a lot and and the same time says very little.