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04-10-2008, 04:59 PM   #1
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Cock-eyed Sigma 20-40 f2.8

Hi folks,

I have a Sigma 20-40 f2.8 which when completely out of focus, will just hunt (well it kinda just moves a little then stops) and will not move along enough to focus. It will only lock into focus if I move the focus ring closer to the correct focus point. But even then, its not locking in at the sharpest focus point.

In otherwords, the autofocus will only lock in when it doesnt have to move too much and even then its not accurate.

Does anyone else have this problem or know why this is?

Thanks in advance.

04-10-2008, 06:01 PM   #2
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are you sure the auto focus in properly engaged?

My Sigma 70-200 F2.8 sometimes does nto fully engage in the drive of my PZ-1.
\
Not sure why, and not really worried about it since i only use the PZ-1 rarely now, (*istD and K10D get the real work).

It might be the same issue with you.
04-10-2008, 09:57 PM   #3
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Hi Lowell,

Not exactly sure whether you mean the lens is clicked into the body properly or the AF-C/AF-S/MF switch is in the right position. However I'm pretty sure its clicked in and the switch is in the AF-S position. I just realised that even when its locking in focus, its not accurate. Seems the only way to get a sharp focus is manually
04-11-2008, 02:56 AM   #4
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QuoteOriginally posted by Wyzard Quote
Hi Lowell,

Not exactly sure whether you mean the lens is clicked into the body properly or the AF-C/AF-S/MF switch is in the right position. However I'm pretty sure its clicked in and the switch is in the AF-S position. I just realised that even when its locking in focus, its not accurate. Seems the only way to get a sharp focus is manually
No, what I mean is if you look closely at the aautofocus drive, it is a little slot on one mount and an engaging tab on the other. This turns when you focus, but on my PZ-1 I have had some trouble getting the two to engage, because there is no gaurantee they alligh perfectly when you mount the lens, they should "snap in" as soon as you focus, but om my pz-1 they don't always do this.

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