Theatrical filmmakers have primarily used 35mm film from the very beginning of movie production, and they continue to use it to this day. This is mainly because it is the established standard. The actual aspect ratio of 35mm film is 1.33:1, the exact aspect ratio used in conventional televisions -- when television was developed, it was a logical choice to model them on the shape of films. This exact ratio was used for most silent pictures, but Hollywood changed the picture ratio slightly with the advent of talkies, to make room for an audio track. The new ratio, 1.37:1, became known as the Academy Ratio and was used for the vast majority of U.S. films until the 1950s. Most movies produced before the 1950s fit conventional television sets fairly well.
But in the 1950s, movie-makers began developing techniques to widen the aspect ratio of their movies. The primary reason for this was the increasing popularity of television; to keep people coming to the movies, Hollywood had to give people entertainment they couldn't get at home. They began making wider and wider movies, featuring spectacular panoramic cinematography. The main thing movie theaters had over television sets is that they could immerse the viewer more deeply in the world of the movie, and the best way to do this was to fill more of the audience's natural field of vision (which has more width than it does height because our eyes are positioned side by side).
In addition to the grandeur and immersing qualities of panoramic scenery shots, wider aspect ratios simply allow for more interesting artistic composition. If you go to an art museum, the vast majority of paintings you see will either be significantly wider than they are tall, a "landscape shape," or significantly taller than they are wide, for a "portrait shape." This is because a more rectangular canvas shape allows the artist to balance the elements of the painting more effectively, which creates a sense of visual harmony. Movies are the same way: A director and a cinematographer can compose shots that are much more pleasing to the eye when they use a wider aspect ratio. The shape of a television screen, which is more square-shaped, severely limits the possibilities for interesting visual compositions.
Since the 1960s, almost all major filmmakers have used a wide aspect ratio when making a theatrical movie. They still use 35mm film with a 1.37:1 aspect ratio, however, so they have to somehow impose another aspect ratio on that film. There are several ways of doing this, and the method the director chooses determines the video producer's options for modifying the film to fit a television screen.
Today, the most common methods of imposing a wide aspect ratio are:
- Anamorphic lens
- Hard matting
- Soft matting
Each method has advantages and disadvantages, and directors often have a personal preference.
One of the most popular ways of producing a wider picture is to "squeeze" it onto the narrower film. This is accomplished with an anamorphic lens on the camera that horizontally condenses the light it takes in. On the actual film of a movie made with an anamorphic lens, all the people and things in each frame appear unnaturally tall and skinny. In the movie theater, the projectionist attaches a similar anamorphic lens to the projector to unsqueeze everything. The advantage of this format is that it uses the entire film area to record the movie picture as it will finally appear, so it doesn't sacrifice any resolution in creating a wide aspect ratio picture. This method limits the depth of focus somewhat, however, and images in the background are sometimes distorted.
A filmmaker can hard matte a film by attaching a special mask to the camera. This mask blocks off the top and the bottom of the scene in front of it so that the film is only exposed to the desired rectangular image. This is cheaper than using anamorphic lenses, and it is a good way for a director to completely control the cinematography of his picture, but, because it only uses the middle part of the available film area, it sacrifices image resolution somewhat.
A filmmaker using this method simply exposes the entire area of the film but composes his picture with only the middle part of the picture in mind. The camera may show only the middle part of the film to the director and cinematographer, or it may have an outline on the entire image that indicates the borders of the desired aspect ratio. When a soft-matted film is projected, the projectionist has to mask it correctly so that only the middle part of the picture appears on the screen. If you go to a lot of movies, you've probably spotted a boom microphone creeping into a shot or seen a movie where people's heads are cut off or there appears to be too much empty space at the top of each shot. These things happen when a projectionist doesn't properly mask a soft-matted film.