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.
What is degenerative disc disease? Nearly everyone's spinal discs show signs of wear as they age. Not everyone, however, will have degenerative disc disease. Not actually a disease, this is a condition in which a damaged disc causes pain. A wide range of symptoms and severity is associated with this condition. Spinal Discs