In article <319D1A99.30DA@magna.com.au>, kelvinl@magna.com.au says...

>I've recently been looking for a second hand 180 or 200mm lens for my
>nikon to do concert photography. I've found a nice second hand 180mm
>f2.8 (Nikkor AIS), but it focuses past infinity. The salesman said
>that's normal for a lens of that age. Should I believe him, or stay >away from the lens? Does that mean it's been bashed around by some
>photojournalist in its past?

David Jacobson got it right, but failed to note that ALL Nikkor
ED-glass lenses are built to focus beyond infinity (since ED glass
contracts/expands more with temperature than other glasses, and as
a result, causes a shift in lens focal length [and barrel length
needed for infinity focus]).
BTW, it is necessary to be careful with (UGH!!!) "canned air",
since it can be cold when it hits the lens, and the uneven
temperature of the glass can cause fracture of front ED elements.
Again, it is not the age of the lens, but the use of ED glass that causes the lens to be built with "beyond infinity" focus capability.
Hope This Helps