Sigma 28-105 f/2.8-4 AF problems or Canon EOS 300 AF malfunctions

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I got Sigma 28-105 f/2.8-4 for my Canon EOS 300 a week ago from Focus Camera and had discovered strange thing - when I adjust focus at 105 mm focal range on 20 m remote object and then turn zoom to 28 mm and press shutter release button, lens focusing ring turns to point in-between 3 and 5 m. I didn't discover such thing on my Canon EF 22-55mm f/4-5,6 USM , of course there is a small difference (focus ring moves seeking focus point) if I zoom from 55mm to 22 mm. Unfortunately at the moment I couldn't check other lenses in same range on my camera. Could someone explain - is this a Sigma lens fault or probably EOS 300 AF malfunction? Thank you in advance.

-- Kristians Luhaers (kristians@mail.lv), August 04, 2000

Answers

If you do a searcj for "Canon EOS Sigma problems" you'll find a long series of threads about this. Its almost certainly the lens, and not the camera.

-- Andrew Schank (aschank@flash.net), August 04, 2000.

This is probably not a fault at all. It simply means that the lens' focus changes as it zooms. Hardly any lenses made these days stay completely in focus as you zoom, even many of the top of the line models change the focus setting as you zoom. The distance indicator is probably set to be reasonably true at either the longest or shortest zoom setting.

-- Jim Strutz (jimstrutz@juno.com), August 07, 2000.

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