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03-13-2010, 03:34 AM   #1
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is my lens sticking

K-x, 50mm M 1.7
I'm outside in broad daylight. Press green button to get metering through manual lens. Result: 1/4000 (etc). Moments later I press it again: 1/3 second. 1/3 second. 1/3 second. Then back to 1/4000 (etc.).
Does this mean something in my lens is sticking?

03-13-2010, 06:06 AM   #2
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Do you have the camera set to M mode? You can only use M lenses in manual mode (all other modes it will only operate wide open). It is possible it is sticking - you can check yourself by flicking the aperture ring with the lens unmounted from the camera.
03-13-2010, 04:45 PM   #3
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QuoteOriginally posted by menifeeminister Quote
K-x, 50mm M 1.7
I'm outside in broad daylight. Press green button to get metering through manual lens. Result: 1/4000 (etc). Moments later I press it again: 1/3 second. 1/3 second. 1/3 second. Then back to 1/4000 (etc.).
Does this mean something in my lens is sticking?
Did you happen to notice the light getting 12+ stops darker?

Something is clearly wrong, maybe even a few things. The lens should only be capable of a 6.5 stop range, f1.7 to f22, unless I counted wrong. Paul is right about checking the lens, but there must be another large factor involved.
03-13-2010, 05:09 PM   #4
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I am using it in M mode. I just tried it again in a completely different setting - indoors where the correct metering was about 1/40. At first it registered 1/3. But I kept pushing the green button and after 5 or 6 presses, it suddenly got it right. From then on it seemed to get it right, so it did seem like it just needed to get unstuck.

When I take the lens off and turn the aperture ring it seems to work fine.

03-13-2010, 08:29 PM   #5
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QuoteOriginally posted by menifeeminister Quote

When I take the lens off and turn the aperture ring it seems to work fine.
Turning the aperture ring will not test for sluggish aperture blades. You need to move the aperture lever at the back of the lens against the spring pressure, then release it. If the blades do not "snap" back immediately, you either have oil fouling on the blades or a weakened spring. Either of these causes will result in inconsistent exposures, but both situations can be fixed by a good lens tech. Also look to see if the lever might be bent and rubbing against one of the sides of its slot. If this is the case, you can gently bend it so that it moves freely in the slot.

Scott
03-13-2010, 11:31 PM   #6
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Did you forget to leave bracketing on? Check to make sure you turn it off - otherwise, the metering is based on your bracketing scheme.
03-15-2010, 06:40 AM   #7
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QuoteOriginally posted by snostorm Quote
You need to move the aperture lever at the back of the lens against the spring pressure, then release it. If the blades do not "snap" back immediately, you either have oil fouling on the blades or a weakened spring.
Scott
Thank you for this explanation - I did not know how to do this.
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