In article <4qpkje$8bg@dodge.eng.sc.rolm.com>, kennethn@clipper.robadome.com says...

>I just bought a used Nikkor 28mm f/3.5. I noticed
>that when the lens is set at the 3.5 notch, a small
>piece of the aperture still is visible in the lens
>opening. To retract the aperture all the way, I
>have to twist the aperture ring beyond the 3.5 notch.

This is not normal, but if the blades show only a very
small amount, I would forget it - the slowing effect
on the lens will be minimal. If you wish to try
loosening the screws on the back face of the bayonette
(carefully - with a metric Philips head screwdriver
[AI/AIS lens only] of the right size [ give the
screwdriver a tap on top before trying to move the
screw]), you may be able to rotate the lens enough
to keep the blades just fully open at the f3.5
click at a position where the screws can be properly
retightened.

>Also, there is an additional aperture setting (unmarked)
>next to the 3.5 setting. Is this usual? Or is my
>lens broken?

It is f4, and is normal.

>I bought it to replace my Tokina 28mm f/2.8, and that
>lens doesn't have those "extra" settings.

If the lens is the f3.5 AI/AIS Nikkor, it is a
first-class 28mm, and is even good wide-open - you
should notice a considerable improvement.
Hope This Helps