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04-19-2009, 09:32 AM   #1
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F-- in LCD panel, with Sigma 28mm lens

Yesterday, while shooting a First Communion, I had an odd problem I think I've only seen once before, too long ago for me to remember what caused it. I was using the K20D with a Sigma 28mm f/1.8 EX lens. Was also using the Metz 58 flash (although I don't think that had anything to do with the problem). Everything was working great for over an hour - and then, for no obvious reason, the LCD panel started to show "F---" where the aperture should be displayed. When I turned the camera off, then back on, I saw that display you see when you use a manual-focus lens that asks what the focal length of the lens is. The lens ring has never been set to anything other than A. (Well, I've moved it off A and then back a couple of times, but I've never USED the camera with the ring set to anything other than A.)

Eventually I got the camera to work normally again. I'm not sure what did the trick. Taking the lens off, wiping the contacts, and mounting the lens again might have done it. But the real question is, what CAUSED the problem to appear suddenly like that? I'm guessing wildly here, but what if the problem was the result of nothing more than a little jostling of the camera that caused the lens mount to be moved ever so slightly? Were that the case, then it's possible that the fix is nothing more than banging the camera again, to get the lens mounted properly once more.

Is it possibly a defect in the lens? I have seen this problem with no other lens that I've used, either Sigma, Tamron or Pentax.

Will

04-19-2009, 10:03 AM   #2
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On the adaptall-2 system you can get f-- message sometimes. Usually it's caused by one or these two things: the electrical contacts being blocked by a non-conductive coating on the tamron adapter out of the factory or the lens not being aligned perfectly with the A contacts (fixed with rotating the lens in a certain direction).

Not sure if the lens might be at fault here or just a blocked A connection. Maybe you wiping the contact have fixed it. I've never gotten this with my other A lens however.
04-19-2009, 10:05 AM   #3
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Hi Will,
I've had the same problem once with a Sigma 170-500. It turned out that the mount screws on the lens had loosened a tiny bit, but enough to cause the intermittened "F" problem.
04-19-2009, 10:14 AM   #4
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QuoteOriginally posted by Andi Lo Quote
On the adaptall-2 system you can get f-- message sometimes. Usually it's caused by one or these two things: the electrical contacts being blocked by a non-conductive coating on the tamron adapter out of the factory or the lens not being aligned perfectly with the A contacts (fixed with rotating the lens in a certain direction).

Not sure if the lens might be at fault here or just a blocked A connection. Maybe you wiping the contact have fixed it. I've never gotten this with my other A lens however.
Andi,

Thanks for the reply. But I'm not sure what the "adaptall-2" system is. I thought (very vaguely) "adaptall" was some sort of conversion system that allowed you to use non-K-mount lenses. But this Sigma 28 is a modern lens and I don't use any kind of adapter, just twist the sucker on the camera like any other lens.

Will


04-19-2009, 10:16 AM   #5
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QuoteOriginally posted by Mile High Quote
Hi Will,
I've had the same problem once with a Sigma 170-500. It turned out that the mount screws on the lens had loosened a tiny bit, but enough to cause the intermittened "F" problem.
Thanks, Mile High, glad to hear that it's not just another case of God singling me out for special punishment.

Did you do anything to get the lens fix? You said it happened "once." I tend to think that things that happen once will happen again. Unfortunately, I rather like this lens! I wonder if I should contact Sigma. I am pretty sure I purchased it less than a year ago, so I'm guessing it's in warranty.

Will
04-19-2009, 10:27 AM   #6
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If I am not mistaken, P/KA lenses have an A contact which protracts in the A setting and retracts when the aperture ring is set otherwise. Perhaps you could check to see if this mechanism is functioning as such? It could be that a spring has become soft or otherwise afflicted.

-Al
04-19-2009, 10:28 AM   #7
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I don't know if there's an easy, or end-user doable, fix for it; but no you aren't alone with this type of problem and Sigma lenses.

The first copy of the Sigma 17-35 EX DG I purchased last year had thet problem on arrival, Will. At least one of the contacts on the lens wasn't prominent enough to make solid contact with the camera contacts. If I flexed the lens slightly it would make contact. I sent it back for a replacement (I understand this probably isn't an option for you since it sounds like you've had yours for a while).
04-19-2009, 11:50 AM   #8
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QuoteOriginally posted by WMBP Quote
Andi,

Thanks for the reply. But I'm not sure what the "adaptall-2" system is. I thought (very vaguely) "adaptall" was some sort of conversion system that allowed you to use non-K-mount lenses. But this Sigma 28 is a modern lens and I don't use any kind of adapter, just twist the sucker on the camera like any other lens.

Will
Adaptall was a mount that tamron made so that they can create one type of lens for all mounts, and SLR owners can just use a corresponding adapter to go with it. I answered it longwindedly but my point is that if the adaptall lenses are of any indication, either the contact is dirty, or the mount is loose to one direction somewhat. Hopefully yours is permanently fixed now.

Cheers =)

04-19-2009, 03:01 PM   #9
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QuoteOriginally posted by Venturi Quote
I don't know if there's an easy, or end-user doable, fix for it; but no you aren't alone with this type of problem and Sigma lenses.

The first copy of the Sigma 17-35 EX DG I purchased last year had thet problem on arrival, Will. At least one of the contacts on the lens wasn't prominent enough to make solid contact with the camera contacts. If I flexed the lens slightly it would make contact. I sent it back for a replacement (I understand this probably isn't an option for you since it sounds like you've had yours for a while).
No, I haven't had it THAT long. I don't know what Sigma's warranty period is but I certainly have had it less than a year - actually I think I bought it earlier this year (2009) so less than 4 months, and I've only used it for a couple of shoots. Up until yesterday it had worked quite well.

I'll see if I can get a response from Sigma customer support on the matter. Thanks for the tip, Venturi,

Will
04-19-2009, 04:41 PM   #10
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QuoteOriginally posted by WMBP Quote
Yesterday, while shooting a First Communion, I had an odd problem I think I've only seen once before, too long ago for me to remember what caused it. I was using the K20D with a Sigma 28mm f/1.8 EX lens. Was also using the Metz 58 flash (although I don't think that had anything to do with the problem). Everything was working great for over an hour - and then, for no obvious reason, the LCD panel started to show "F---" where the aperture should be displayed. When I turned the camera off, then back on, I saw that display you see when you use a manual-focus lens that asks what the focal length of the lens is. The lens ring has never been set to anything other than A. (Well, I've moved it off A and then back a couple of times, but I've never USED the camera with the ring set to anything other than A.)

Eventually I got the camera to work normally again. I'm not sure what did the trick. Taking the lens off, wiping the contacts, and mounting the lens again might have done it. But the real question is, what CAUSED the problem to appear suddenly like that? I'm guessing wildly here, but what if the problem was the result of nothing more than a little jostling of the camera that caused the lens mount to be moved ever so slightly? Were that the case, then it's possible that the fix is nothing more than banging the camera again, to get the lens mounted properly once more.

Is it possibly a defect in the lens? I have seen this problem with no other lens that I've used, either Sigma, Tamron or Pentax.

Will
It happened to me. Many years(about 10) ago I bought a Sigma 28-105/f2.8-4.0. Shortly after the warranty expired(go figure!) mine did the same thing. Luckily I shoot weddings and the lens has an aperture ring so exposure was not a problem using a manual flash with my ZX-60. When I got my K10D, I started really fumbling with the contacts, the ring, and whatever else on the lens out of frustration. Then one day I got an aperture reading, but the ring was set to 2.8, not A! I still tried messing witn the ring and finally it became a little harder to turn and now it is working normally again. The ring stays in th A position now and I have not had a problem since. I also have no clue as to why.

Last edited by res3567; 04-19-2009 at 04:48 PM.
04-19-2009, 05:18 PM   #11
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Will,
The "F" thing happened several times and it drove me nuts, since there was no rhyme or reason to it. The lens worked one shot and didn't the next. I was going to take the mount of to see what the problem might be and noticed that the mountscrews weren't tight. I tightened them and the problem hasn't reoccured since.
04-19-2009, 06:16 PM   #12
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QuoteOriginally posted by Mile High Quote
Will,
The "F" thing happened several times and it drove me nuts, since there was no rhyme or reason to it. The lens worked one shot and didn't the next. I was going to take the mount of to see what the problem might be and noticed that the mountscrews weren't tight. I tightened them and the problem hasn't reoccured since.
Mile High,

The "mount screws" that you tightened - is this mount on the camera body, or are you talking about something on the lens itself?

I guess tomorrow when it's bright again I'll get my tiny tools out and see if there's anything loose that I could tighten. Hadn't thought of doing that yet.

Will
04-19-2009, 06:33 PM   #13
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Will,
the screws that I'm talking about are on the back of the lens and hold the part that mounts to the camera in place. Both of my Sigma lenses have three screws.
Marco
04-19-2009, 07:19 PM   #14
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QuoteOriginally posted by Mile High Quote
Will,
the screws that I'm talking about are on the back of the lens and hold the part that mounts to the camera in place. Both of my Sigma lenses have three screws.
Marco
Thanks, Marco. I'm going to look at this carefully tomorrow. I appreciate your input and also everybody else's responses.

This really was weird - and a little embarrassing, as I was working with clients at the time and it's always better to look like you know what you're doing than vice versa. :-)

Will
04-20-2009, 09:51 AM   #15
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I have now taken the lens off and checked the screws, both on the lens and on the camera. My wife thinks I personally have a few screws loose, but the screws on the lens and the camera body seem to be okay. I didn't try hard to tighten them but I didn't notice any looseness at all.

So I'm not sure what to think. Guess it's time to contact Sigma customer support and see if I have any options there. Thanks again to everybody who responded.

Will
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