SUPER 35: 35MM - 2:35:1
Super35 movies are matted to a 2.35:1 aspect ratio. When such movies are displayed on TV or in a non-widescreen manner, the top and bottom mattes are removed, thus displaying more of the frame that was intended although there is normally a small portion cut off the sides as well. Only live-action scenes in Super35 movies have the mattes removed. Super35 scenes with special effects are hard-matted at 2.35:1 and must undergo the pan-and-scan process to fit the screen, thus resulting in a loss of about 45% of the original image.
The live-action image above is from James Cameron's “Terminator 2”, which was filmed in Super35. The red outline shows what part of the frame was originally shown in theaters. The blue frame shows what is seen on the non-widescreen version.
Many movies made in Super35 are transferred to video with the top and bottom of the frame restored, so that you actually see more of the picture on video than you did in the theater. However, scenes which include special effects in them are almost always filmed hard-matted in the appropriate widescreen ratio and therefore must be subjected to the pan-and-scan process.
SOURCES:
http://www.widescreen.org/widescreen_matted.shtml
http://www.widescreen.org/aspect_ratios.shtml