AF Fine Tuning Lens Identification
Prepared 2007-12-31 (149/109444) by Bill Claff

All Nikon CPU lenses contain a "chip" and that chip has both a lens ID and chip ID.
Both of these IDs are unique between Nikon lenses.

Non-Nikon CPU lenses reuse Nikon lens and chip IDs.

The AF Fine Tuning feature appears to use either the lens ID or chip ID to identify the lens; and this will work perfectly with Nikon lenses.

However, if you have any non-Nikon lenses that conflict with a Nikon lens that you own, or you have multiple non-Nikon lenses with the same IDs; then you will have a conflict since you can only save one set of AF Fine Tuning values per ID.

One serious overuse of an ID occurs with the following group of Sigma lenses that all have the same lens and chip IDs as the 300mm f/2.8D ED-IF AF-S Nikkor:

I have confirmed this behavior with my Sigma 30mm and Sigma 100-300mm lenses.

Nikon could make the firmware "smarter" and have it use other information such as focal length in addition to the ID but they have no motivation to help non-Nikon lens manufacturers.

BTW, once an ID is in use by AF Fine Tuning it remembers the focal length and aperture information until that lens is removed from the list.

Here's another set of lenses that would appear identical to each other: