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12-04-2010, 02:57 PM   #1
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Problem with Sigma Lens

I have been using a Sigma EX 70-200 2.8 for several years to shoot wrestling. Today, I kept getting the F-- in the exposure window. I don't know why. It didn't happen on every shot, but it happened way too much! I took the lens off of my K20D and tried it on my K100 body and had the same problem. Does any one have a suggestion as to what the problem could be--- or where I could get some quick service.

12-04-2010, 03:05 PM   #2
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turn the aperture ring back to the A position
12-04-2010, 03:13 PM   #3
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Thanks for your response.

I tried that. I still get the F-- . Any more suggestions! I am getting desperate!
12-04-2010, 03:14 PM   #4
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clean the contacts on the lens with a soft pencil eraser or damp cloth

12-04-2010, 03:27 PM   #5
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Oh no,

That didn't work! Now, when I turn on the camera.... in any mode I get a blinking F--. It will not even let me change the F-stop using the rear control.
12-04-2010, 04:10 PM   #6
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I'll be watching this thread for hints, as my Sigma 14mm f/3.5 is experiencing the same problem. I took a bunch of shots in 'A' / auto modes, they were all shot wide open and came out very soft. Works great in full-manual mode.
12-04-2010, 04:49 PM   #7
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Is there any play in the lens when mounted, prohibiting the contacts from touching? I get this at times with my extension tubes with long, heavy lenses.
12-04-2010, 06:18 PM   #8
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Hoping for some more insight.

There is no play in the lens keeping if from making contact. It won't even work in Full Manual Mode Now....

12-04-2010, 06:49 PM   #9
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Do you have an ohm meter? Check the resistance to the A pin from the lens mount It should be less than about 10 ohms. It sounds like you have lost contactto this pin. Also confirm that other lenses still work
12-04-2010, 07:36 PM   #10
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Where is the A pin?

I do have access to an ohm meter.
12-04-2010, 07:42 PM   #11
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This particluar lens

Is not working on my *istDL, K100, or my K20D! I was actually thinking that it might be a camera issue...so, I tried all three bodies.
12-04-2010, 07:50 PM   #12
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I have to believe this is probably a contact problem with the pins.
I have had a similar problem with my Sigma 28-105 f4 for the past couple of years, since it was new. Normally I just put pressure on the lens as though I am trying to wiggle the mount and it corrects itself, occasionally I have to remove and remount the lens.
Though I've never had it happen while I was shooting.

I do like the lens so I too will be watching for some kind of solution.
12-06-2010, 07:45 PM   #13
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Speaking for my 15mm, I fear it's the little circuit board. My old ohm meter shows little movement so it isn't grounded, and I opened and cleaned every metal contact
(and spent 1/2 hour reinstalling the ball bearing that makes the f-stops click ). Not much else to try in the obvious dep't.. and I fear Sigma wants $100 just to undo
three screws much less solve anything. Bummer. Oh yeah, I wiggled aperture ring & mount; no change, always F--.

Any other suggestions?
01-07-2011, 08:50 AM   #14
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Hello

I have had that with a sigma 70-300 DG.
The unique solution was to have it repaired by Sigma and now two years later still no problem.

Best regards,
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