11. Power contacts on the lens mount were introduced to enable Pentax's SDM DNG ). 12. The X-mount lens mount has a short flange back distance of just 17.7 mm. 13. The lens mount design is an important issue for compatibility between cameras and lenses. 14. An infrared filter was mounted just behind the lens mount . 15. In 1982, Cosina began to manufacture lenses in a variety of SLR manufacturers'lens mounts . 16. And to give them flexibility, one or two versions also had lens mount adapters. 17. The special Calypso lens mount is of the bayonet variety with an O-ring sealing. 18. The lens mount is a passive e-mount with Canon EF or Nikon F mount adapter. 19. Adapters may not be available to bridge every combination of lens mount and camera mount. 20. The manufacturers of these lenses have reverse engineered the electronics of the EF lens mount .