sentences:  Some of the newest A-mount lenses are designated "DT" for Digital Technology; these are for digital cameras with APS-C sensors, and will result in vignetting if used on a film SLR or a full frame DSLR or full frame SLT camera.Third-party lenses for the AF lens mount are made by Zeiss, Sigma, Tamron, Tokina and Vivitar.The Nikon F-mount was introduced by Nikon in 1959, and is thus one of the most venerable lens mounts still in existence.