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Time Freeze · 12-12-2007, 08:29 PM

I have a Sigma UC Zoom 28-70mm AF lens that my K10D thinks is a manual focus lens. When I switch from MF to AF I can feel the camera engage the lens as a AF (the focusing ring gets more resistant when I turn it) but the view finder indicates that it a MF lens. Other Sigma lens work fine on the 10D and this lens works fine on my ZX-5. Any ideas what may be causing this. I used an alcohol pad to clean the contacts but it did not help. THe K10D also won't show the f stop it just indicates F--.

Thanks,
John

Jodokast96 · 12-12-2007, 08:58 PM

Sounds like the contacts aren't quite, well, contacting. I sometimes run into this when using all of my extension tubes with a heavier lens. There is the tiniest bit of play that seems to be just enough to keep one of the contacts from touching. Once I play with it a bit it's fine.

blende8 · 12-13-2007, 01:18 AM

Does the lens have an aperture ring?
Is it set to "A"?

Time Freeze · 12-13-2007, 05:32 AM

Yes it does but that should not affect either the autofocus or the display of the f stop.

blende8 · 12-13-2007, 06:28 AM

If the lens is not set to A, you will see "F--" in the display.

Time Freeze · 12-13-2007, 10:45 AM

Sorry, I didn't realize that. F-- is displayed when the lens is set to A. It seems strange that this is the only lens that is not communicating with the K10D but will work fine with the ZX-5.

**Canada_Rockies** · 12-13-2007, 11:30 AM

Originally posted by Time Freeze

Sorry, I didn't realize that. F-- is displayed when the lens is set to A. It seems strange that this is the only lens that is not communicating with the K10D but will work fine with the ZX-5.

TF - you have faulty contact between the lens and the body. This is confirmed by the F-- viewfinder display.

Make sure the mount is not loose on the lens/body.

Make sure all the little contact "ball bearings" move freely in the lens - it is not impossible for a bit of grit to be holding one of the contacts up too high to make good contact with the body lens mount.

Hope you find the problem soon.

12-12-2007, 08:29 PM	#1
Time Freeze New Member Join Date: Nov 2007 Location: Long Island, NY Photos: Gallery \| Albums Posts: 8	K10D not regonizing AF lens as AF I have a Sigma UC Zoom 28-70mm AF lens that my K10D thinks is a manual focus lens. When I switch from MF to AF I can feel the camera engage the lens as a AF (the focusing ring gets more resistant when I turn it) but the view finder indicates that it a MF lens. Other Sigma lens work fine on the 10D and this lens works fine on my ZX-5. Any ideas what may be causing this. I used an alcohol pad to clean the contacts but it did not help. THe K10D also won't show the f stop it just indicates F--. Thanks, John

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12-12-2007, 08:58 PM	#2
Jodokast96 Veteran Member Join Date: Oct 2007 Location: Erial, NJ USA Photos: Gallery \| Albums Posts: 2,134	Sounds like the contacts aren't quite, well, contacting. I sometimes run into this when using all of my extension tubes with a heavier lens. There is the tiniest bit of play that seems to be just enough to keep one of the contacts from touching. Once I play with it a bit it's fine.

12-13-2007, 01:18 AM	#3
blende8 Veteran Member Join Date: Feb 2007 Location: Bremen, Germany Photos: Albums Posts: 1,521	Does the lens have an aperture ring? Is it set to "A"?

12-13-2007, 05:32 AM	#4
Time Freeze New Member Join Date: Nov 2007 Location: Long Island, NY Photos: Gallery \| Albums Posts: 8 Original Poster	Yes it does but that should not affect either the autofocus or the display of the f stop.

12-13-2007, 06:28 AM	#5
blende8 Veteran Member Join Date: Feb 2007 Location: Bremen, Germany Photos: Albums Posts: 1,521	If the lens is not set to A, you will see "F--" in the display.

12-13-2007, 10:45 AM	#6
Time Freeze New Member Join Date: Nov 2007 Location: Long Island, NY Photos: Gallery \| Albums Posts: 8 Original Poster	Sorry, I didn't realize that. F-- is displayed when the lens is set to A. It seems strange that this is the only lens that is not communicating with the K10D but will work fine with the ZX-5.

12-13-2007, 11:30 AM	#7
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by Time Freeze Sorry, I didn't realize that. F-- is displayed when the lens is set to A. It seems strange that this is the only lens that is not communicating with the K10D but will work fine with the ZX-5. TF - you have faulty contact between the lens and the body. This is confirmed by the F-- viewfinder display. Make sure the mount is not loose on the lens/body. Make sure all the little contact "ball bearings" move freely in the lens - it is not impossible for a bit of grit to be holding one of the contacts up too high to make good contact with the body lens mount. Hope you find the problem soon.

K10D not regonizing AF lens as AF

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