<p>In response ot Robin Smith, I think you have to look at the history of Nikon's metering for the F to understand the reasons behind the indexing.<br>
<br />The first coupled meter for the F was not through the lens, it was integrated in a prism, but the cell faced the world. Kind of like the original Leicaflex. To make this work, the meter needed to know what actual aperture the lens was set at.<br>
<br />Now when moving to a TTL meter, it doesn't really need to know what the actual aperture the lens is set at for open-aperture metering. The meter needs to know how many stops down from wide open the aperture is set for. And there came the funkiness. Nikon had a method for communicating the actual aperture, but not a method for communicating how many stops from wide open the lens was set. The indexing procedure, mount at f/5.6, twist to wide open, and to minimum, set a stop at the maximum aperture, I think by a purely mechanical operation.</p>
<p>I have to guess that Nikon engineers knew all they needed to measure was the delta from wide open. I would not be surprised to learn that they kept the old "bunny ears" index because of a requirement to stay compatible with existing lenses and/or because some other manufacturer held a patent on a system to communicate "stops down from maximum" to a meter.</p>
