A dedicated ttl through the lens remote for use with canon dslrs and the latest interfit s1 series of monolights the s1s ttl remotes give the users direct control over any s1 light in any shooting mode from the camera position this camera mounted transmitter is available for canon nikon and sony cameras and supports e ttl ii i ttl and p ttl protocols respectively having three individual groups gives users the freedom to control lights individually to create dynamic lighting ratios with