 The spring that opens or closes the lens iris in the K-mount lenses may have to be reset to work in the opposite direction.Although the Nikon F-mount back-focus at 46.5mm is well above the 44mm of the SD14, there is no adapter for the infinity focusing possible as, unlike with Canon EOS, the Nikon bayonet of roughly the same diameter will not fit inside the SA–PK bayonet.The M42 thread does, as taken care of by Asahi when introducing K mount in the 1970s, and therefore all M42 lenses work as is without problems with the SA/M42 converter.