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03-25-2010, 08:58 AM   #1
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Problem with automatic lens

Hi all,

I recently purchased a new Quantaray zoom on eBay. The problem with this lens is that most of the time, the lens appears as manual (F--) to the camera. If I rotate the lens body to one side, the camera then recognizes it as an automatic lens. But operating the zoom usually throws it back off.

I contacted the seller and they refunded my money and let me keep the lens, so I'm not out anything. But now I'm wondering if there's a way to diagnose/fix the problem so that it can still be usuable without being so finicky?

My gues is that the contact that makes the camera think it's in 'A' mode is not lining up properly, but why would that happen?

03-25-2010, 09:02 AM   #2
Ira
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QuoteOriginally posted by tfischer Quote
Hi all,

I recently purchased a new Quantaray zoom on eBay. The problem with this lens is that most of the time, the lens appears as manual (F--) to the camera. If I rotate the lens body to one side, the camera then recognizes it as an automatic lens. But operating the zoom usually throws it back off.

I contacted the seller and they refunded my money and let me keep the lens, so I'm not out anything. But now I'm wondering if there's a way to diagnose/fix the problem so that it can still be usuable without being so finicky?

My gues is that the contact that makes the camera think it's in 'A' mode is not lining up properly, but why would that happen?
What camera? Do you have "Use Aperture Ring" enabled?

And that "F--" is normal for many lenses.
03-25-2010, 09:18 AM   #3
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QuoteOriginally posted by Ira Quote
What camera? Do you have "Use Aperture Ring" enabled?

And that "F--" is normal for many lenses.
Sorry, should have been more specific.

This is a fully automatic lens (both aperture and focus). It *should* work without the F--

Camera is a K20D.
03-25-2010, 09:24 AM   #4
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Make sure the aperture ring is in the "A" position

03-25-2010, 09:30 AM   #5
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QuoteOriginally posted by MrApollinax Quote
Make sure the aperture ring is in the "A" position
It is.

Just to reiterate: If it shows 'F--' in the viewfinder, I can take the lens barrel and wiggle it side to side (without changing ANYTHING else) and then it will work - untiil it gets wiggled again.

I have numerous other lenses and know how to work the camera
03-25-2010, 09:40 AM   #6
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Try cleaning the contacts on both the camera and the lens mount - should help (use an eraser or some alcohol).
03-25-2010, 09:51 AM   #7
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As mentioned above, cleaning the contacts should help. Also, it's possible the pin hole in the lens is slightly too big, which would allow the lens to rotate a bit and not touch the electrical contacts properly. The lens should not be able to wiggle back and forth at all when it's mounted and clicked in properly.
03-25-2010, 09:55 AM   #8
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QuoteOriginally posted by GoremanX Quote
The lens should not be able to wiggle back and forth at all when it's mounted and clicked in properly.
It's very slight, but does appear to be more than my other lenses.

Any practical way to fix that?

03-25-2010, 10:09 AM   #9
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QuoteOriginally posted by tfischer Quote
It's very slight, but does appear to be more than my other lenses.

Any practical way to fix that?
Not really. But check to make sure the pin hole in the lens isn't obstructed in any way. Maybe the pin isn't able to insert fully for some reason. Other than that, I can't think of any practical way to make that hole "smaller".
03-25-2010, 10:09 AM   #10
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QuoteQuote:
It's very slight, but does appear to be more than my other lenses.

Any practical way to fix that?
I have some lenses that wiggle like that but I always thought it was the bayonet wiggling. I doubt there's an easy way to fix that...
03-25-2010, 05:18 PM   #11
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I played with this a bit more tonight.

I thought maybe the internal switch that grounds out the 'A' pin when you have the lens in 'A' mode was being flakey, so I put a multimeter on it, and it appears to be just fine, off the camera. So something is screwy between the lens and the camera.

Since the AF linkage lines up properly, I'm not sure how the contacts would be getting out of line, unless the lens is manufactured improperly, or if there's more 'give' in the AF system than in the contacts.

One thing that is strange about this lens compared to my others: Most lenses I've seen have a shiny metal back plate. This one has a black (painted?) black plate, and a small copper contact on one of the bayonets that appears to be what grounds it (I used that contact for my tests with the multimeter). I can take a pic of it if people don't understand what I"m talking about. It's possible that this grounding contact isn't making good contact with the camera, but it wasn't very adjustable.
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