Documentaries are meant to be attempts to get at the truth. Both the films under consideration here contain a central concern with exposing something fundamental about a complex subject. The Fog of War is focused at blowing away some of that fog so that key principles governing the conduct of nations and those charged to lead them can be explored. Capturing the Friedmans also suggests the idea that something elusive can be caught.

One of the key ways in which documentaries suggest they are telling the truth is by being made in ‘fly-on-the-wall mode. This requires the filmmaker to create the illusion that the camera (and any other crew) is invisible. Whatever the subject, it then looks as if they are going about their business, as they would do if the camera were not present. Of course, from the earliest days of the cinema, when this mode has been employed, it was always illusory because the often-dramatic incidents these films delivered up to us (as with any feature film) invariably had others present filming or recording sound. It is also the case that careful adjustments of ‘the real’ had to be made to accommodate the earliest camera equipment.

So, for example, Robert Flaherty’s pioneering 1922 film Nanook of The North features scenes in which the Inuit family, which is its focus, hunt and catch a walrus. To catch this ‘authentic’ tradition, Flaherty actually required the family to re-enact a practice that had long gone out of fashion.

In the same film, scenes shot inside an igloo necessitated the building of a special set with a wall removed so that the cumbersome camera equipment could be accommodated.

Another Flaherty film called Man of Aran (1934), told the tale of people living off the coast of Ireland and showed a shark hunt. Again, this was a practice that was almost extinct and an expert had to be brought in to teach the locals how to do it, before the cameras started rolling.

Another early documentary-maker was called John Grierson and sequences from his 1929 film Drifters about the herring fishermen of the North Sea required the redesign of the herring boat cabins, again so the bulky cameras of the period could be accommodated.

So the search for truth has often involved documentary-makers in subterfuge and re-enactment.