Good day Javier,
Greetings.
1. ADR allows you to see the aperture in the viewfinder and it works with
all types of Nikkor lenses (other than non-AI lenses). Basically you might
have observed that there is another aperture scale on the lenses in small
letters just behind the main aperture scale (and closer to the mount).
These small letters are reflected via an optical arrangement and appear in
the viewfinder. This is ADR. Not all Nikon SLRs provide this feature.
Examples of cameras which provide this feature are F3, F4, F5, FM2, etc. It
was originally devised during the days when lenses had no CPUs and hence
this was the only way to show the aperture set in the view finder. Now a
days lenses have CPUs and relay the information so that you get the exact
aperture (not just the set aperture) in the viewfinder LCD display.
2. IMHO means "in my humble opinion"
Trust this clarifies your doubts. Happy shooting.
Regards
