Fujinon XF2X TC WR Multiplies focal length of FUJINON XF50-140mmF2.8 R LM OIS WR and FUJINON XF100-400mmF4.5-5.6 R LM OIS WR by 2x Weather-resistant design for weather- and dust-resistance and operation in conditions as low as 14 Degree Fahrenheit Uses 9 elements in 5 groups Does not affect lens AF speed Camera displays and records information reflecting the change in aperture and focal length when theteleconverter is mounted.