In article <4t48bd$2h3s@news.doit.wisc.edu>, danforth@hp-124.cae.wisc.edu says...
>I was wondering if any of you may be able to help me. I
>own a Nikon 8008s with a Nikkor 28-70 f/3.5-4.5. I have
>had these items for three years and have recently had problems
>with the autofocussing. The autofocus will "hunt" in
>certain situations. The focus ring will spin repeatedly from
>minimum to maximum focus even when I'm focussing on objects
>with plenty of contrast and texture in bright light. I'm also
>aware of the problem of focussing on a series of parallel
>horizontal or vertical lines, so that's not the problem.

This may be worth a try: put the shutter speed on "B",
remove the lens, hold the shutter-release firmly down to
keep the mirror up (and the shutter open), and blow air
(a large squeeze bulb works) on the two sensors on the
bottom of the mirror box. (The AF sensor may be dirty.)

>Since I only have one AF camera and lens, I don't know
>which one is giving me the problem. I have noticed that
>there is a slight fuzziness in focus if I, for example,
>manually focus the lens on an object at 28mm and then zoom
>it out to 70mm, the object becomes ever so slightly out of focus.
>I also get this effect in going in the other direction.
>(There is some word for the fact that most zooms do not change
>focus with changing focal length - I can't remember).
>Additionally, if I have the camera in continuous autofocus mode,
>and focus the lens on an object, and then zoom lens slowly,
>the camera will adjust the continually tweak the focus
>as I zoom.

Most Nikor zooms are slightly "varifocal" - they shift focus
a touch with zooming, which makes the advice in the instruction
books about zooming to the long end to focus, then back to shoot
(for greatest focus accuracy), absurd.

>I don't expect any of you to be repair techs, but I'd like
>to know if this is typical behavior for my system in good
>working order (I doubt it). The camera is under extended
>warranty with Mack Camera in NJ. I have sent it to them
>once already with this problem. They "repaired" it (in
>12 weeks) and sent it back.

This is not typical (much as I detest AF ;-).
If you send it back to them, ask them to clean the AF system,
and see what it is like when it returns....

>Finally, what can I do in the worst case, where the camera
>is indeed not working properly, and Mack camera says it is
>working properly? What are my chances of telling my story
>to Nikon and getting more than a free subscription to their
>magazine?

Nikon repair is often slow to recognize a problem that I
think is obvious, but once they try a repair, they are excellent
at finally solving the problem (after several tries, maybe...).
And, hey, don't knock their magazine - they once ran a story/photos
on my work! ;-)
Hope This Helps