The more I think about it, the more fatuous (or do I mean specious?) this quote seems.
No photograph is "the truth," but then, nothing is (to a modern, or certainly a postmodernist).
So what if he'd said, "All photographs are accurate. None of them is true"? That seems a bit more accurate to me. But then consider the first part: "All photographs are accurate."
If accurate means correct in all details (cf. Lexico), then this is false since many photos - especially in fashion magazines! - are doctored in some way, from soft focus to color correction to airbrushing Trotsky out of a the photo of Lenin's speech in Sverdlov Square.
Now, to the extent that Trotsky was no longer an important figure in Soviet history after the rise of Stalin, editing him out of the photo was true in its context. Which takes us around 180 degrees to, "No photographs are accurate. All of them are the truth."
