FX

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FX is Nikon's term for a sensor which is the same size as traditional 35mm film. Lenses behave in the same way they behave on Nikon's film cameras. DX lenses can only be used when the FX sensor is in 'crop' mode, effectively making it a DX sensor.

The first Nikon FX camera was the Nikon D3, followed by the Nikon D700 and the Nikon D3X.

FX cameras have a shorter focal depth than DX cameras for the same lens focal length, and lenses behave as if they were 1/3 shorter, which is the same way they would behave on a 35mm film camera. The larger photosites on an FX camera mean that, for the same resolution and technology, less noise is recorded, and so the camera can be used at a higher ISO for equivalent image quality.