28-85 FD oil problem?

My 28-85 has developed an oily imprint of the diaphram on an internal element, even though the diaphram itself doesn't appear oily. It seems to be affecting central contrast. Has anyone else encountered this problem? Is it a known problem with this lens (the element must be very close to the diaphram)? What to do? I'm reluctant to give up on the lens, since it's the best short zoom I've ever used - in my personal experience, better than the reputed 28-70L USM.

Dan:

 

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This sometimes happens if you leave the lens in the sun. The

lubricant reflows, resulting in what you see. The main thing that

occurs once the oil gets inside the lens is that the diaphragm will no

longer stop down properly. Be sure to keep checking this, since

eventually, the diaphragm will stop working.

 

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You may have to take this to a repair facility to be fixed.

 

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John