‘I look at the footage to convince myself that you were alive’: how Ross McElwee made a film about unimaginable loss, grief and guilt

When his son died aged 27, the director could barely bring himself to watch his old clips of the boy. When at last he did, it was the genesis of an extraordinary project It feels crass to compliment Ross McElwee on his latest documentary, Remake, because it is not the picture he…