The upcoming Nikon NIKKOR Z 600mm f/4 lens is rumored to have a built-in teleconverter similar to the NIKKOR Z 400mm f/2.8 TC VR S lens ($13,997) – most likely 1.4x, which will make the lens be equivalent to 840mm f/5.6. The new 600 will be extremely sharp and expensive. I was told that the new Nikkor Z 600mm lens with the teleconverter will be sharper than the current NIKKOR AF-S 800mm f/5.6E FL ED VR lens ($16,297) and even charper than the recent NIKKOR Z 800mm f/6.3 VR S lens ($6497). The official announcement is rumored for late 2022 but that can easily slide to early 2023.
Nikon Z lens roadmap: telephoto apertures “measured” and calculated
A potential patent for the NIKKOR Z 600mm f/4 lens can be found here:
The latest Nikon Z lens roadmap can be found here: