The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Nikon 800mm f5.6E FL ED VR and the Nikon 85mm f1.8G for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Nikon 800mm f5.6E FL ED VR is the longer of the two lenses at 461mm. The Nikon 85mm f1.8G with a length of 73mm, is 388mm shorter. Besides being longer, the Nikon 800mm f5.6E FL ED VR also has a larger diameter of 160mm compared to the Nikon 85mm f1.8G's 80mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Nikon 85mm f1.8G weighs 350g, 92% (4240g) lighter than the Nikon 800mm f5.6E FL ED VR's weight of 4590g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Nikon F (FX) Mount for size comparison purposes.
Telephoto Prime Lenses in Nikon F (FX) Mount for Size Comparison
Lens Mounts
Both the Nikon 800mm f5.6E FL ED VR and the Nikon 85mm f1.8G has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Focal Range
Nikon 800mm f5.6E FL ED VR is a prime lens with fixed focal lenght of 800mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 1200mm.
Nikon 85mm f1.8G is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 127.5mm.