oil trace on 3rd 35 cron

[j._b.]

I have recently got an old 35 cron(27***). I have just noticed there are some shallow shiny traces of oil on the blade. Is that normal?

 

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Thanks.

[albert_smith]

Here is a thread from the archive on this subject.<a

href="http://greenspun.com/bboard/q-and-a-fetch-msg.tcl?

msg_id=007Jzs"> Oil on aperture blades </a>

[jay_.]

It may very well not be oil. The diaphragm blades on older Leica

lenses tend to become polished in spots where they rub together and

looking through the glass elements it can look a lot like oil. Tilt

the lens around, work the aperture ring. If the "oil" spots look

symmetrical and you can't see any movement of a liquid nature, it

probably isn't oil. But it's really hard to 'phone in an accurate

diagnosis.

[john_hicks___]

Since it's not an auto-diaphragm in most cases oil on the blades wouldn't matter.._however_ there is/was at least one Leica lens in which if the diaphragm blades were impeded by gummy oil they could bow out and scrape a nearby element. I don't remember what lens that was.

 

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Also, oil on the blades can be deposited (usually by heat) onto the nearby glass surfaces and leave permanent marks/spots in the coating that'll persist even after the oil is cleaned off. This happened to an old 35 Summilux I once had.

 

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So if it's clearly oil and not shine from wear, it's time for a CLA.

[giles_poilu]

J.B., I have the exact same lens and the exact same 'appearence' of

oil.

 

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Jay is perfectly correct (another 3rd gen. owner I believe?) , it is

probably not oil - if you look very closely as you move the ring back

and forth you will see that the marks are very uniform polishing

marks created as the blades rub on each other.

 

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Nothing to worry about - rest assured you have (IMO) the best version

of the 35 'cron non-asph!