i have a 50-500mm that will not auto focus.

jon pafford · 08-16-2010, 02:48 PM

The aperture will not lock in the a position. I hear the lens trying to auto focus but it will not auto focus. Also, the focus meter does not move when the aperture is in the a position and I hear the lens motor. i tried the lens on a k7 and km.

SpecialK · 08-16-2010, 02:59 PM

Sigma had potential autofocus problems in a batch of 150-500s. Not sure if the 50-500 was affected. You should contact Sigma.

GaryH · 08-16-2010, 04:23 PM

I am assuming you have the older lens Like I do without HSM. Look at your focus ring from above. There should be a set of two lines marked AF and M. Make sure the focus ring is pushed forward towards the front of the lens to the AF line. If you use the lens for manual focusing, both the lens and camera have to be set to manual.

Hope this works

08-16-2010, 02:48 PM	#1
jon pafford Forum Member Join Date: Jul 2007 Location: houston texas Photos: Albums Posts: 80	i have a 50-500mm that will not auto focus. The aperture will not lock in the a position. I hear the lens trying to auto focus but it will not auto focus. Also, the focus meter does not move when the aperture is in the a position and I hear the lens motor. i tried the lens on a k7 and km.

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08-16-2010, 02:59 PM	#2
SpecialK Pentaxian Join Date: Dec 2006 Location: So California Photos: Gallery Posts: 16,481	Sigma had potential autofocus problems in a batch of 150-500s. Not sure if the 50-500 was affected. You should contact Sigma.

08-16-2010, 04:23 PM	#3
GaryH Site Supporter Join Date: Oct 2009 Location: Philadelphia, Pa Photos: Gallery Posts: 764	I am assuming you have the older lens Like I do without HSM. Look at your focus ring from above. There should be a set of two lines marked AF and M. Make sure the focus ring is pushed forward towards the front of the lens to the AF line. If you use the lens for manual focusing, both the lens and camera have to be set to manual. Hope this works