The "FUJINON TELECONVERTER XF2X TC WR" is a high-performance teleconverter capable of multiplying the focal length of mounted lenses* by two. It features excellent optical design with a construction of 9 elements in 5 groups to maintain the optical performance of the original lens. Also, thanks to the unified design when mounted to a compatible lens, the teleconverter is weather and dust-resistant and operates at temperatures as low as -10°C. This makes it possible to be used with confidence outdoors when used with the weather and dust-resistant X-T1 and X-Pro2 camera bodies, and the XF50-140mmF2.8 R LM OIS WR and XF100-400mmF4.5-5.6 R LM OIS WR lenses.
A firmware update is required for the "XF50-140mm F2.8 R LM OIS WR" and "XF100-400mm F4.5-5.6 R LM OIS WR" lenses in order to provide full compatibility. This firmware is planned to be available at the beginning of June 2016. Please note that when updating firmware, make sure to update the latest camera firmware before updating the lens.
Please refer to the following website for information on how to confirm your firmware version and its update methods.