T-mount has a long flange distance of 55mm and most 35mm cameras have shorter flange distances, a simple mechanical adapter called T/T2-Ring is needed to adapt a T-mount lens to any camera body without optical correction to achieve infinity focus.The differences between T-Ring and T2-Ring is that a T2-Ring consists of an inner ring with T-mount thread and an external ring with corresponding lens mount. Both rings are held together by 3 peripheral screws on the external ring. Slackening these screws allows rotation between the lens and the camera body. This is especially useful when the camera body is attached to telescopes or microscopes.
Non-Auto camera lenses, slide-duplicators, bellow units, astronomical telescopes, microscope adapters and a number of other attachments can be mounted onto various SLR camera bodies with the help of relevant T-2 adapters.
