Back in the days of 35mm film, a 50mm prime was considered a 'standard' lens. That's because it gives pretty much the same perspective as viewing a scene with the human eye, without the magnification of a telephoto lens or the shrinkage a wide-angle lens uses to squeeze more into the frame.
The flexi disc (also known as a phonosheet or Soundsheet, a trademark) is a phonograph record made of a thin, flexible vinyl sheet with a molded-in spiral stylus groove, and is designed to be playable on a normal phonograph turntable.
The intervertebral discs (or discs) are fibrocartilages lying between adjacent surfaces of the vertebrae. They form a fibrocartilaginous joint between the vertebral bodies, linking them together. The disc makes up one third to one fourth of the spinal columnâs length, forming an interpose between every two vertebrae except between the atlas (C1) and axis (C2) and coccyx.