Refers to Nikon cameras that feature a 35mm film-frame size sensor. Nikon digital SLRs have either an FX or a DX sensor. The FX sensor, measuring 23.9 x 36mm, is roughly equivalent to the size of the 35mm film frame. The DX sensor is smaller, measuring 15.8 x 23.6mm. The FX sensor, with more light gathering area, offers higher sensitivity and, generally, lower noise. There is, of course, no crop factor present with the FX sensor.