G Sears
> I'm looking at a Nikon lense. How can i tell if it is AI, or non AI?
> Its a 50mm f1.8 Nikkor SN: 1781813 Nikon.
>
> I've researched and i understand the difference in function but i cant
> tell which is which just by looking. Is there a feature that stands
> out that would help me identify this lense?
>
> Yep, I'm just another newbie trying to learn so please flame me in
> private. :-)
The easy way to tell if a Nikkor is AI or non-AI is to check the rear-facing
edge of the aperture ring. AI/AIS/E/AF/I/S/P Nikkors will have a couple
of ridges extending slightly rearward (one catches the AI meter tab on AI
bodies); the non-AI aperture rings will have a smooth, uniform rear edge
all the way around. (BTW, DO NOT mount a non-AI lens on an AI body
[a few will permit it, if the body AI tab can be lifted out of the way]), or you
may damage the body AI tab. Another give-away that a lens is AI: the
presence of a second smaller set of aperture numbers on the aperture
ring. Also BTW, there were several barrel versions of the Nikkor 50mm
f1.8, though only two optical versions: the larger, metal-barrel version
(both in AI and AIS); and the versions using the more compact optics
(AIS-compact [both metal and plastic-barrel versions], E [two versions],
and AF [two versions]). Optical quality is similar and excellent, though
the E versions are not multicoated, and the compact versions trade a
slight amount of wide-aperture edge performance for a lack of linear
distortion. Probably more than you wanted to know...;-)
Hope This Helps
David Ruether - http://www.fcinet.com/ruether