On Wed, 02 Sep 1998 23:59:03 GMT, tamio@lava.net (Tami Osterstock) wrote:

>Awhile back I posted about a focusing problem I was having with a
>Nikon AF 24-120 D lens (it wouldn't come into focus at infinity).
>Well, I returned that lens to Nikon for repair. They deemed it
>un-repairable and sent me a new one. Now, with the new one, the right
>side of my prints comes out *very* *very* soft. The problem is most
>apparent at wide apertures (f5.6 @ 120mm, f4.8 @ 50mm). I checked
>both sides of the lens for smudges on the exterior glass, but it looks
>clean. While looking at my "test target", a section of newspaper
>classifieds taped to the wall, you could tell through the viewfinder
>that the right side was not coming into focus. I was very careful to
>make sure everything was level and parallel when I photographed my
>test target.
>
>Despite my relaying all this to Nikon, they are starting to hint that
>my camera may be the problem. They say that a lens won't be out on
>just one side. Has anyone ever had a lens that exhibited a similar
>problem, where the problem was indeed with the lens, and not the
>camera? The first 24-120 lens I had didn't exhibit this kind of
>problem. And, I have a 35-135 that looks perfectly sharp, edge to
>edge in the viewfinder. (I haven't conducted a "classifieds" test
>with the 35-135 yet, but I may well do it if it means not having to
>send my camera body to Nikon.) I have a hard time believing that my
>camera is the problem here. Anyone have any comments on this issue?

I would have a VERY hard time believing it is the camera, unless
it is a viewing artifact only and does not appear on film (try
a distant subject, like a detailed horizon line [city, woods, etc.],
since this removes alignment error on your part...). Since other
lenses appear OK, I think there is probably nothing wrong with the
camera. Unequal focus and/or unequal sharpness at opposite sides
of the frame are the FIRST thing I check for with zooms, since poor
lens alignment is fairly common. The next is equal focus/sharpness
in the four corners. Most WA and wide-to-short tele zooms fail these
checks by at least a small (but noticeable) amount, tele zooms less
often (though two of three 70-300's that I checked had this fault
near the 70mm end of the range). Oddly, even with film evidence,
Nikon repair folks seem unable to detect this optical flaw (even
when it is perfectly obvious in the viewfinder...), and are unable
to fix it. I would take the infinity-photos and return the negatives
or slides with the lens and ask for another replacement...