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Old Nov 12, 2010, 8:12 PM   #1
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Default Sticky iris

Vivitar 28-70mm PK-A lens

The iris seems to be sticky. Sometimes it works, sometimes it doesn;t.

What can be done about it?
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Old Nov 12, 2010, 8:15 PM   #2
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Take a look at the aperture blades from the back of the lens. Set the aperture ring to a small aperture and then use the lever to actuate the blades several times - do you see oil on the blades? I have a Kiron lens with oil on the blades and it can be fixed. But it would require someone taking apart the lens and then cleaning the blades - the labor is more than what it would cost to buy another one on ebay.
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Old Nov 13, 2010, 3:35 AM   #3
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Simplest action is to just use the lens in manual mode.
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Old Nov 13, 2010, 4:33 PM   #4
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Hi fofa,

Another possibility is a bent actuator lever. I recently had a lens where the lever was bent so it rubbed against one side of the slot it travels through. This extra friction caused the aperture mechanism to slow down enough to give erratic exposures.

Try the test that Harriet suggested, but also take a good look at the lever to see if it stays centered in the slot.

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