The Fujifilm XF 1.4x WR Teleconverter is a high-performance teleconverter capable of multiplying the focal length of mounted lenses* by 1.4x. Although the aperture becomes one f-stop higher when mounted, the teleconverter features an excellent optical design with a construction of 7 elements in 3 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 camera body and XF50-140mmF2.8 R LM OIS WR lens. High image quality design which maintains the optical performance of the original lens Construction of 7 elements in 3 groups maintains the optical performance of the original lens. By using the optimal image quality parameters for the overall characteristics of the original lens and 1.4x teleconverter, an excellent imaging performance with great aberration suppression can be achieved even when the focal length is multiplied by 1.4x. The camera's autofocus performance is unaffected by the addition of the teleconverter AF speed remains the same as the lens by itself when the teleconverter is mounted. Also, accurate focusing at super-telephoto focal lengths with shallow depth of field is possible thanks to the AF performed by the image sensor. Weather and dust-resistant and -10°C low-temperature operation Using the teleconverter with a weather-resistant camera and lens, such as the “FUJIFILM X-T1” premium mirrorless camera and the “FUJINON Lens XF50-140mmF2.8 R LM OIS WR”, does not affect the weather resistance of the system. High-grade subtle appearance The teleconverter's high grade metal exterior has been designed in unity the X system. When it is attached to a compatible FUJINON lens, the two products appear as one single lens.