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01-31-2012, 12:16 PM   #1
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lens staying open

Sears 28mm f2.8 pk mount aperture works smooth and proper when off the camera but goes wide open when on the camera when in manual mode.Same lens worked properly yesterday.
Thanks,
Jake

01-31-2012, 12:18 PM   #2
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Do you mean, when you change the aperture (I assume it's an aperture ring manual lens?), it doesn't stop down when you shoot?

And it worked properly previously?
01-31-2012, 12:31 PM   #3
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QuoteOriginally posted by bjake Quote
Sears 28mm f2.8 pk mount aperture works smooth and proper when off the camera but goes wide open when on the camera when in manual mode.Same lens worked properly yesterday. Thanks, Jake
It shouldn't stop down until you actually shoot, so what you are describing is completely normal. This is the intended behavior unless the lens has a auto/manual diaphragm mount, which almost no K-mount lenses do.

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01-31-2012, 12:38 PM   #4
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Lens is staying open when taking pictures,no difference in exposure whether set on f22 of f2.8.1/2000 gives near proper exposure at iso 200 with lens set to f22.Just put another lens on,Sears 50mm 1.7 which works properly.
Thanks,
Jake

01-31-2012, 02:44 PM   #5
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QuoteOriginally posted by bjake Quote
Lens is staying open when taking pictures,no difference in exposure whether set on f22 of f2.8.1/2000 gives near proper exposure at iso 200 with lens set to f22.Just put another lens on,Sears 50mm 1.7 which works properly.
Thanks,
Jake
Do you use the GREEN button and if so what does it do?
If nothing, then you may have had the same issue I and others had with a very easy fix (see here ).
01-31-2012, 02:50 PM   #6
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Don't use green button,gust guess exposure and adjust by how it looks on the screen.Will check out your link.
Have put two more manual lens on the KX that work properly.Put the lens that didn't work right on a k1000 ,with the back open and shutter on B and it worked properly.
Thanks,
Jake
02-01-2012, 05:25 PM   #7
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Does the screen darken when you crank the preview lever? Is there any mechanical noise when you do it? If so the lever may be bent and not catching the body mechanism.
02-01-2012, 06:01 PM   #8
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QuoteOriginally posted by derekkite Quote
Does the screen darken when you crank the preview lever? Is there any mechanical noise when you do it? If so the lever may be bent and not catching the body mechanism.
Don't know what a preview lever is.Is also my guess that the lever on the lens might be bent.did move it out slightly but lens is still staying open.This lens doesn't have a thin stamped lever like most lens but one that has been cast and machined.
Thanks,
Jake

02-01-2012, 08:38 PM   #9
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On my K5 it is on the on-off switch. I think the green button will do the same, activate the aperture mechanism.
02-01-2012, 11:39 PM   #10
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Green button does stop down the lens but at the same time the mirror flops but am able to look into the lens to watch the aperture.Measuring with a machines the lever seemed to be a few thousands toward the center than other lens so I pushed it out slightly and is now working.Will dig out my depth mike tomorrow to check farther.
Thanks,
Jake
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