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05-09-2011, 08:11 AM   #1
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Stuck wide open at 3.5 ?

I have a 80-200 Focal lens (yes, I know,probably best used as a very long and heavy lens cap) that is stuck wide open. The aperture ring makes all the right noises but nothing changes. Is there any way to lock it in at a more useful aperture?
Thanks in advance..Ken

05-09-2011, 08:33 AM   #2
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Is it PK or M42? If M42, does it have an M/A switch? You say the "aperture ring makes all the right noises" -- so it doesn't turn smoothly, stoplessly? Such would be a sign of a bearing gone loose. Does the actuator pin or flag move? DOes that cause the iris blades to move? More details, please!!
05-09-2011, 11:53 AM   #3
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Have you read the article on how to use manual lenses on a DSLR? Start by clicking the "Articles" link at top. Short answer: you have to shoot in "M" mode for K-mount lenses.
05-09-2011, 12:45 PM   #4
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More information

Sorry about the lack of detail. I don't have the lens with me but I'll try to be accurate.

1-When I take the lens off the camera and look through the lens as I manually change the aperture, the lens remains fully open. The aperture ring makes the clicking sound at each aperture like my other lenses.

2-When I manually flick the lever on the mounting end of the lens while looking through the lens, nothing changes.(On other lens that I have this lever changes the aperture, then springs back.

3-(It is a K lens and the iris blades do not move.)

thanks in advance...

05-09-2011, 01:08 PM   #5
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It may be time to order that DA* 60-250/4.

The most common cause of this is oil on the aperture blades, providing just enough extra friction to stick them together and fully open. On most lenses, the aperture blades are inconveniently located in the middle of everything, so a repair might get involved.

Third-party lenses sometimes fail in a way that's much easier to fix. The aperture lever on the mount has a spring on it, so it snaps back like it should. But the mount is a two-part design so it can be easily adapted to other systems, and there's a second spring inside the lens that might have broken or gotten unhooked.

If you remove the mount screws and mount, you can usually figure out what's wrong by figuring out how the aperture lever was supposed to move the blades. Hope for a dangling spring that can be rehooked. Otherwise, often a slotted screwdriver can move the part that moves the blades. If you try to move the blades and it's hard, you'll see the oil on them too. Then it's a matter of getting access to the blades and a good cleaning with naptha or mineral spirits.
05-09-2011, 02:51 PM   #6
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Dave has it right. I rather like my Focal / K-Mart lenses, but they were inexpensive, and if one failed like this, I wouldn't hesitate to do some exploratory surgery. One can learn much too much about lenses this way!
05-09-2011, 02:55 PM   #7
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Thanks Just1MoreDave, I got this lens with others in a old camera bag from the local EcoThrift. If I can fix it following your instructions, great. If not, it's all part of the experience. I'm off to find out via Google a source for naptha or mineral spirits.
Ken

I considered getting the DA* 60-250/4 but my wife suggested that we spend the money on our house payment instead.
05-09-2011, 03:53 PM   #8
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I had the same thing happen to a Canon FD 50/1.8. One year, it worked perfectly. After sitting for another year, the aperture wouldn't close. So now I just use it as a magnifying glass, which normally you'd need a reverse adapter for (to hold the aperture open when off the camera.)

Paul

05-09-2011, 04:06 PM   #9
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QuoteOriginally posted by kenhreed Quote
Sorry about the lack of detail. I don't have the lens with me but I'll try to be accurate.

1-When I take the lens off the camera and look through the lens as I manually change the aperture, the lens remains fully open. The aperture ring makes the clicking sound at each aperture like my other lenses.

2-When I manually flick the lever on the mounting end of the lens while looking through the lens, nothing changes.(On other lens that I have this lever changes the aperture, then springs back.

3-(It is a K lens and the iris blades do not move.)

thanks in advance...
If everything mechanical is in place, this sounds like oil on the blades to me.

When you take the lens off of the camera and set it to f22 (or whatever the largest number is) the iris should close all the way down. Flicking the lever should open them and allow them to snap back. The lever itself is spring loaded and the blades are probably on their own spring. If you have oil on the blades, it will actually create a vacuum between them causing them to stick.

Edit: I didn't read the entire thread so +1 to Dave.

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