I hope this question finds its way to Robert Harris, but perhaps another member will know the answer as well. In chapter 9, of "Vertigo", where Jimmy Stewart and Barbara Bel Geddes are visiting the Argosy Bookstore, and are about to depart; the scene grows very dim, in the manner of a rapid fade--not a fade to black, mind you. The effect has the appearance of an exposure problem rather than a lighting issue, but, I noticed that after the characters are outside the bookstore, and the shop is in plain view behind them, the lights come up rapidly, and the interior of the shop is brightly lit once more. Does anybody know what took place during the scene? I can't imagine Hitchcock letting it slide at the time of production, being such a perfectionist.