How did they pull focus and frame on "Soy Cuba" if the infrared filter blocked visible light to the reflex?

[Geffen Avraham]

I just watched Soy Cuba yesterday and was stunned by the cinematography. It was a masterclass in what a human being can do with a camera.

I was particularly impressed by the infrared scenes - but how did they shoot them? It's not enough to use infrared film, to get that look you need to block out visible light. This presents a problem, as while the film can see infrared, you cannot, and the view in your reflex finder will be dark.

Some cameras, like the CP-16, Arriflex 435, or Panaflex, have the ability to put filters behind the mirror, but as far as I know this movie was shot on a Cameflex or Konvas, which do not.

How did they frame and pull focus? The shots in that film are always in motion and incredibly dynamic, and require a deft operator. Did they film most of this movie flying blind?

[Mark Dunn]

In practice you can use a filter that passes some visible light so that reflex viewing and pulling focus are practical.

https://www.ilfordphoto.com/shooting-infared-extended-red-film-guide/

From that article, it's clear that you need a film that only sees the near infrared, otherwise you couldn't get enough exposure for 24fps.

Of course you can focus by scale and not rely on the finder at all, or use video assist- something like what Doug Milsome did on Barry Lyndon.

Edited November 12 by Mark Dunn

[David Mullen ASC]

I'm sure shooting on an 18mm helped a lot in that regard... You can re-mark your lens to compensate for the focus shift.