Hi there... the question was "what exactly is aperture direct readout?" ADR is a mechanism for allowing you to view the aperture ring on the lens directly through the view finder of the camera. This is handy with the F4, which cannot control the aperture setting electronically. For the F5, if you have AF lenses, or D lenses, it is not needed, as the aperture is read directly in the LCD in the viewfinder electronically. It is useful when using non AF lenses... Hope this helps... Paul Silver Paul Silver Photography & SilverLight Studios Stock, Commercial & Fine Art Photos... Architecture, Interiors, Industrial Imaging http://www.silver-light.com See my Portfolio at: http://www.silver-light.com/portfolio/ [EMAIL PROTECTED]