The Nikon D800E is a special edition of the D800 that minus the effects of an optical anti-aliasing filter.
It is so sharp that the D800E should in theory, rival medium
format digital back in resolution!
In digital cameras, the anti-aliasing filter is also known as an optical lowpass filter or blur filter or AA filter.
Such a filter involves a tradeoff among sharpness, aliasing, and fill factor. In a monochrome or three-CCD or Foveon X3 camera, the fill factor alone, if near 100% effective with microlenses, can provide a significant anti-aliasing effect,while in color filter array (CFA, e.g. Bayer filter) cameras, an additional filter is generally needed to reduce aliasing to an acceptable level. - Wikipedia