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12-31-2010, 03:30 PM   #1
littledrawe's Avatar

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so what if there IS oil on the aperture blades

I have a takumar fisheye and there is oil on the blades. How does this effect the lens' function?

12-31-2010, 03:34 PM   #2
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Oil on the blades slows the action down. For automatic apertures this can lead to irregular exposure. On a tak unless you are using it on a sPotmatic it won't domanything because the aperture is manually stopped down
12-31-2010, 03:36 PM   #3
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Doesn't the oil spatter on the lens element?
12-31-2010, 04:30 PM   #4
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My K20/4 had oil on the blades and it caused regular over exposure. (The blades were not closing fast enough.)

I sent the lens to Eric and all is well.


12-31-2010, 04:57 PM   #5
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Thanks Lowell! I am really excited about this lens. My copy is in amazing condition when I bought it they said it came from a collector and it literally looks like it has never been used. As I was giving it a closer inspection I noticed the oil. I wasnt sure if this was a result if it not being used often or how it gets there. Mentioning the oil is usually a point people make in their ebay listing so I was curious to know what effect it has.

I keep hearing more about this "Eric" does he have magical powers?!
12-31-2010, 05:48 PM   #6
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Congrats on a nice lens pickup. As to oil on the blades, yes it can cause the blades to become sluggish or stick, but it affects exposure only if the blades are being stopped down just before the actual exposure; otherwise that doesn't matter at all. If you are planning to use this on one of the DSLR's, then you need not worry about this, as you'll have the lens in M and the aperture will always be stopped down to what you have set. You'll only have the issue if you're planning to use it on an M42 body (and don't want to set the lens to Manual). The only other issue is the one Ira mentioned, that there is the supposed possibility that the oil could migrate from the blades to the elements, but I don't think I've actually heard of a case of this happening. My opinion is not to worry about that very much (my Macro-Takumar has oily blades as well).
12-31-2010, 06:06 PM   #7
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"I keep hearing more about this "Eric" does he have magical powers?!"

Pretty close.
He just saved my old Tamron zoom that my daughter dropped with a filter in place (T.G.) The smashed filter would not budge as the rim was badly distorted. He also cleaned up my fine old Pentax K 200MM F2.5 to like-new condition and functioning. He will get my LX on it's next tune up.

Fast and reasonable.

Eric Hendickson
Pentax Repairs
188 Shoffner Rd
Sharps Chapel, Tn 37866

(865) 278-1051

09-08-2013, 10:53 PM   #8
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I am very interested in this topic. I wonder why the oil is there in the first place. Is it to allow free and smooth travel when used? #2. Since oil is a lubricant, how can it cause the blades to become sluggish and sticky? Does this mean that after some time had passed, that the oil becomes similar to a gooey substance and makes everything work harder than they should? Thanks for your assistance.


09-08-2013, 11:03 PM   #9

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Yes, oil makes the blades sluggish. If only a little bit on a m42 lens where you aren't using auto aperture, it doesn't matter much. However, it can lead to starburst effects and such in night shots -- increases internal reflections. Some lenses it is easy to get rid of and some it isn't depending on the type of grease that is breaking down to create the oil.
09-09-2013, 12:55 AM   #10
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If you are determined to clean it off yourself, disassemble the lens down to the aperture mechanism. Stop the lens down to f/22 and with a steady hand, with a soft paintbrush clean the aperture blades using zippo lighter fluid which removes oil quickly and effectively.
09-09-2013, 10:14 AM   #11

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QuoteOriginally posted by littledrawe Quote
I noticed the oil. I wasnt sure if this was a result if it not being used often or how it gets there.
My K24/2.8 got hot when it was being used
in a harsh industrial environment,
and got sluggish (overexposing) after that.
The oil must have run.
Eric fixed it.
09-15-2013, 08:27 AM - 1 Like   #12
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The aperture blades normally only overlap each other to provide light tightness. There is clearance of a couple of thou (0.002 inches). The area of overlap varies with the set aperture and a tiny film of lubricant which has migrated from part of the outer mechanism which does require oil causes a bit of damping dependent on the viscosity of the oil. As the blades are fully open just before the shutter fires and then have to stop down only during the exposure and cameras can fire several times a second the blades must be free running. The aperture lever shuts the blades but only quite weak springs open them afterward to prepare for the next exposure. Increasing the power of the return springs would probably shorten the life of the mechanism. I have manual iris diaphragms in microscope condensers with about twenty blades which are lubricated with thick grease. I had this problem with Carl Zeiss Jena M42 lenses but have been lucky with the many and varied K mount lenses I have owned.

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