The RTS III is not AF. You will be able to use any of the lenses you get now with an RTS III with full functionality. If you get a 167 MT or an RX or an AX (which is auto-focus, but focuses using the body, not the lens, so your old MF lenses will work, and even auto-focus!) which have Program or Shutter priority modes, you will want to get MM (Multi-Mode) versions of the lenses. Only Contax N1/NX bodies and lenses are not compatible with the older Contax/Yashica-mount lenses and bodies. The N1/NX are auto-focus that focus with the lens, not the body, and have a unique, proprietary lens mount that is not backwards compatible.