In article
>I just received a new zoom lens, mail order, and was surprised to find
>that the focus ring turns a significant way past infinity. So far, in
>fact, that there's no way that a photo taken with the focus ring at
>the infinity stop would be in focus when fully zoomed in (the infinity
>mark goes about 1/8" past the index).
>I don't expect perfection in the position of the infinity stop, but
>this is much further out than I've ever seen before. However, it
>doesn't prevent me from taking good pictures, it just makes infinity
>focus a little harder to find.
>It's over 10 years since I bought a new lens. Is this considered
>normal these days? Or should I return the lens? For the record, it's
>a Sigma zoom, price about $150.
If the lens had "ED" or similar elements, the lens would normally allow
focus beyond infinity to allow for changes in focal-length with
temperature. At $150, this is unlikely, and may be simple misadjustment,
or it could be intended to cover shifts in focus with zooming (not
uncommon, even in expensive zooms - and why one should NOT focus at
the long end of the zoom range and then zoom back to shoot [as many
instruction books used to advise doing]).
Hope this helps.