Almendros shot it in the twenty minutes a day that worked

A production that shoots only at magic hour is a production that has surrendered its schedule to its cinematographer. Everything else — the crew's day, the actors' availability, the number of setups possible before the light goes — arranges itself around one person's decision about how the film should look.

That is not a technical contribution. That is a production being reorganised around an aesthetic argument, and the person who made the argument was Almendros.

Haskell Wexler shot a substantial portion of the film after Almendros left for a prior commitment, which complicates the attribution rather than settling it, and the two men disagreed publicly about the proportions for years. The disagreement is itself the point: two people cared enough about authorship of these images to argue about it in print, which is more than the vocabulary of the auteur allows for.