oil on blades caused by . . .

[bokenikon]

I had a Leica 50mm 'Lux Asph that was barely a year old and started showing a couple drops of oil on the blades. Fixed under warranty. I recall before the condition showed up I took the lens on an airplane flight, an international trip that involved over 25 hours total (roundtrip) of airtime. My question is whether spending so much time in an arid environment (airline cabins are around 12% humidity, I think) may have had something to do with the oil on the blades. The lens was not in the cargo hold, it was on me the whole time.

 

[jonmanjiro]

I don't see how low humidity could cause oil to migrate to the aperture blades. I expect excessive heat is more likely to be the culprit. Did you leave your lens anywhere where it could have been subject to excessive heat?

 

[DNG]

when you are not using your manual lenses, close down your f stop all the way in storage this will prevent oil on the blades.

when the blades are open the widest f stop they are all on top of each other and if there's any oil from the focusing mechanism or other areas close to the iris control mechanism that oil could get on the blades.

 

[Sarcophilus Harrisii]

when you are not using your manual lenses, close down your f stop all the way in storage this will prevent oil on the blades.

when the blades are open the widest f stop they are all on top of each other and if there's any oil from the focusing mechanism or other areas close to the iris control mechanism that oil could get on the blades.

I have to confess to being skeptical this would help in most cases. If oil is close enough to the control ring to contaminate it, then it is likely to be close enough to get on the ends of the blades. At which point, oil will be likely to spread across the surfaces of the aperture blades as they slide across each other. At best, I'd suggest you'd be postponing the inevitable, if it actually helps at all, which I doubt. Do you have any references for your suggestion please?

Cheers
Brett

 

[alistair.o]

As has been said:

1. Close down the F stop when not in use.

2. Stand on end (do not lay them side on)

3. Store them out of the sun.

 

[jonmanjiro]

I have to confess to being skeptical this would help in most cases. If oil is close enough to the control ring to contaminate it, then it is likely to be close enough to get on the ends of the blades. At which point, oil will be likely to spread across the surfaces of the aperture blades as they slide across each other. At best, I'd suggest you'd be postponing the inevitable, if it actually helps at all, which I doubt. Do you have any references for your suggestion please?

Cheers
Brett

I have to confess that I agree with this. I don't think the position of the aperture blades while the lens is in storage is going to make the slightest bit of difference.

No doubt there are exceptions, but generally in a lens the aperture mechanism runs dry and the only lubricant is in the focus helical. Which means that lubricant on the aperture blades is caused by lubricant migrating to there from the focus helical. Grease is supposed to stay where its put, but if it gets heated excessively its viscosity can drop and it can migrate to places where its not supposed to be (such as the aperture blades). That's why in my previous post I asked if the lens was subjected to excessive heat at some point. Would be interested to hear what the OP says about that.

 

[bokenikon]

Don't remember placing the lens next to any abnormal heat sources. I did travel during the wintertime so MAYBE at a point I don't recall it was next to a heat source (underneath a bus seat, etc).

 

[Sarcophilus Harrisii]

I have to confess that I agree with this. I don't think the position of the aperture blades while the lens is in storage is going to make the slightest bit of difference.

No doubt there are exceptions, but generally in a lens the aperture mechanism runs dry and the only lubricant is in the focus helical. Which means that lubricant on the aperture blades is caused by lubricant migrating to there from the focus helical. Grease is supposed to stay where its put, but if it gets heated excessively its viscosity can drop and it can migrate to places where its not supposed to be (such as the aperture blades). That's why in my previous post I asked if the lens was subjected to excessive heat at some point. Would be interested to hear what the OP says about that.

These were my thoughts also, but you've written them down more eloquently than I did, thank you.