This year is expected the release of the Nikon AF-S Nikkor 200-400mm f/4E ED VR
According to the source, this year Nikon will release a new version of a full frame lens covering a focal length range of 200-400 mm with a constant maximum aperture of F/4.
The current model AF-S Nikkor 200-400mm f/4G ED VR II shown in the illustration, was presented in spring 2010.
The new model will be equipped with an electromagnetic diaphragm and a built-in switchable teleconverter, which increases focal length by 1.4 times. A similar solution is applied in telephoto lens Canon EF 200-400mm f/4L IS USM Extender 1.4 x.
The announcement is expected to close by the end of the year. The source is confident that this year Nikon will present one full-frame telephoto lens — Nikkor AF-P 70-300mm f/4.5-5.6 VR. From its predecessor with the same combination of focal length and maximum aperture it will be different stepper drive auto focus.
Source: Nikon Rumors