Tele Vue Nikon Wide 2.4" T-AdapterNikon F Mount Wide T Adapter for Tele Vue Imaging System The typical T ring telescope setup does not take advantage of the wide aperture of the bayonet mount: significant vignetting is caused by the constriction of the T ring opening. Our new Nikon F Mount Wide T Adapter with Bayonet (NWT 2073) connects to Nikon F mount camera in place of the T ring and provides 13% greater aperture to minimize vignetting. The other side of this adapter fits our