In movies, one size never fits all.
By now, most home theater fans have undoubtedly grown used to seeing letterbox bars on many movies they watch. In today’s high-definition era, any content with an aspect ratio that’s greater than a 16:9 (a.k.a. 1.78:1) HDTV screen must be presented with black bars on the top and bottom of the frame. Blu-ray viewers have many examples of this. Approximately half of all modern theatrical films are photographed in the scope aspect ratio of 2.40:1. Iron Man, Tropic Thunder, and Wall-E fall into that category. Scope photography is sometimes referred to as 2.35:1 for reasons that are too complicated to explain in detail here. Just know that 2.40:1 is technically correct, although many people in the industry continue to use the term 2.35:1 interchangeably. At the other extreme, material narrower than 16:9 (classics like Casablanca and The Adventures of Robin Hood are 1.37:1) will have pillarbox bars on the sides. In the middle, movies composed for 1.85:1 (such as the The Sixth Sense, Hellboy, or Knocked Up) nearly fill an HDTV.