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02-18-2012, 07:31 PM   #1
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Sears Auto 28mm 2.8 stuck wide open?

Bought this lens from a forum member and apparently it worked fine on his K20D. However, when mounted on my K-x (or even when unmounted), the aperture blades appear to be stuck wide open. There's no "A" setting, and the aperture ring does nothing. Tried M, Av, Tv modes, and still aperture won't budge...Am I missing a step here? Would there be any difference in the way the K20D or K-x would handle this lens? Or did I just get a lemon?

02-18-2012, 07:37 PM   #2
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Yup, I think you're missing the fact that the aperture won't stop down until you actually take a photo. Then it pops right back up.

Try taking the lens off your camera. Your the aperture ring work then? If so, then there's nothing wrong with the lens

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02-18-2012, 07:38 PM   #3
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Is it an M42 screwmount or PK bayonet mount lens? If it's a PK, and has no A setting, then you sjpi;d set your camera to M(anual). Have you read the sticky on using manual lenses on dSLRs? That may give more help.
02-18-2012, 08:05 PM   #4
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Thanks for the quick reply guys...it's a PK mount btw. And yes, even off-camera, rotating the aperture ring does nothing. While mounted, I thought it would work the same as my M 50 1.7 where it stops down as I take the photo. Still no go. Using the green button, f2.8 is metering the same as f16. Bokeh looks the same at f2.8 and f16, as well.

And yup, had it on Manual. I seldom use Av (even when available), coz my K-x loves to underexpose . And I find I just get more reliable results with M.

Anyway, I'm pretty sure I went over the Manual lenses sticky a while back, but I'll go through it again just in case I missed anything.

02-18-2012, 08:12 PM   #5
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Darn, I was really hoping that the lens was OK, but now it's starting to sound like the aperture might be stuck. Maybe it got damaged during shipping?

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02-18-2012, 08:21 PM   #6
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Maybe...who knows. It was packaged well, though. Believe me, I was just as hopeful as you ...oh well, at least I got it cheap (albeit under the impression that it worked fine). I guess this is going on the attempt-to-repair-it-myself-one-day pile along with my CZJ Tessar 50 2.8.
02-19-2012, 05:38 PM   #7
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Can you manually move the lever on the mount end of the lens? Off camera the aperture should be closed. The lever is held open by the body and stops down when you shoot or meter. Maybe the lever is bent and preventing the aperture from operating.
02-19-2012, 05:50 PM   #8
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I can move the lever fine, but it doesn't do anything. On or off camera, aperture is wide open regardless. Tried taking shots while looking closely into the front of the lens. Basically, I never see the aperture blades.

02-19-2012, 06:10 PM   #9
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QuoteOriginally posted by arsn.r3d Quote
I can move the lever fine, but it doesn't do anything. On or off camera, aperture is wide open regardless. Tried taking shots while looking closely into the front of the lens. Basically, I never see the aperture blades.
Seems like stuck aperture blades due to oil. Can you return the lens to the seller or a refund?
02-19-2012, 07:02 PM   #10
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QuoteOriginally posted by ducdao Quote
Seems like stuck aperture blades due to oil. Can you return the lens to the seller or a refund?
Yeahhh..I actually got this back in Christmas hehe. I did bring it up with the seller then, but he swears to it working fine on his K20D (or, maybe he had no idea it wasn't working properly at all? I dunno). I just got busy with the holidays, work, and other stuff, I haven't gotten around to using it again on my K-x till recently...Anyway, I got it fairly cheap though, so probably wouldn't be worth the postage and hassle of returning it. I had a feeling it really was stuck aperture blades, but I was hoping maybe, just maybe, I was missing a step, or that somehow there was a difference in the way the K-x and K20D treated the contacts...Oh well. Looks like I'll have to go all Macgyver on this lens ...whenever I get around to it anyway.

Thanks for all the insight everyone!
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