What is the T-Mount system? What are T-Adapters and T-Rings?

T is for Tamron, a long-time maker of lenses and accessories to fit many different makes of cameras. They devised the system in the 1950s-1960s to sell their lenses to fit other makes of camera bodies.The T-mount system consists of four parts: the camera, a T-Ring, a T-Adapter and lastly a lens or a telescope.


The T-Mount system uses T-Threads of metric dimensions (42mm and 48mm diameter and a pitch of 0.75mm) to mate cameras to lenses or telescopes. The T-Ring is the object which fits into your brand name camera on one side and has female T-Threads on the other side. T-Rings are made and sold to fit specific camera bodies; the two Celestron T-Rings available are the T-Ring for Canon and the T-Ring for Nikon. The T-Adapter is the object that will connect your telescope or lens to your camera with its male threads. Each T-Adapter is uniquely designed fit either Schmidt Cassegrain or EdgeHD optical tubes along with the size. You cannot place an 8" EdgeHD T-Adapter on an 11" EdgeHD optical tube and vice versa. T-Adapters are made and sold to fit lenses and telescopes, as well as other devices such as bellows. When screwed together, the matching threads on the T-Ring and T-Adapter allow a camera to be rigidly mounted to a lens or a telescope.