you could see a tiny ring which adjusts aperture settings, in L position (locked) for D3x, D3, D300, D700 (new generation), when in lock position, this lens will allow you to see the view finder in all open apertrue setting of f3.5, although you may have steped down to several stops smaller, the little round rubber button near the lens logo, is for you to see the actual depth of field at apertrue settings you have chosen for your picture (before you shoot), next to it is the Tilt switch, it could be locked by a very small knob, directly on the opposite side of the lens, you will need to un-lock that locking knob before you could adjust tilt functions freely, directly under the rubber-apterture button, is the shift adjust knob, and opposite to it is the locking knob to hold it from shifting easily, (out of position)
there is a "triangle shaped" rotation release button just right hand side of the shift knob, this will allow you to rotate the lens 45 to 90 left and 45 to 90 degrees right, total of 180 degrees rotation,
it is full of fun, and full of challenges, whenever this lens is used in the field, special purpose? yes, this is why it is worth to have it, it is very unique, someday, wish can own all 3, ...........