Slightly Oily Nikon 100mm 2.8 Series E

[Carl]

I've just acquired a Nikon 100mm 2.8 series E (to use on a 5D). It's in great condition, except for one issue: 3 of the aperture blades have a bit of oil on them.

I took a few test shots, and was quite pleased (so no effect on image quality, and I suspect I've at least got an average example). Is the oil likely to be a problem? Not that I'm using it as an auto-aperture lens, but the movement of the blades seems fast (doesn't seem to be effected by the oil). How would I clean the blades?

[Carl]

Here's a wide-open test shot. Focus is slightly off, so the focus is actually nearer the camera than the tree.

[Carl]

Here's the 100% bottom left crop I tried to up load previously.

For reference, RAW processing with DPP, colour balance 5500K, sharpening set to 0.

[Jieffe]

I use that lens on my Pentax and that baby is very sharp wide open ! Not bad at all for an entry-level lens.

[poilu]

nice lens, great colors & 3D

[luisalegria]

The oil is bad only if it affects the operation of the blades. By itself it should have no effect on the image. If your blades are moving well, no problem. Maybe after some time the oil will degrade and cause the blades to stick, but I would not bother cleaning the blades until that has actually happened.

I have cleaned oil from sticky blades on several lenses, it can be easy or difficult depending on the construction of the aperture mechanism and how easy it is to disassemble the lens to get to the blades.

[cooltouch]

Nikon's Series E lenses are usually excellent optically, especially the 100mm f/2.8. I've owned one of these before, and I thought it was a great little lens. Series E lenses' only drawbacks are 1) they aren't as robust as their Nikkor counterparts and 2) they don't have the prong on the aperture ring to index with older Nikon meters. If you take reasonably good care of your equipment, then 1) is not an issue. If you're not using the lens on an old Nikon camera with the old-style meter post, then 2) doesn't matter either.

[Carl]

Thanks for your comments. I've now managed to upload the crop of the photo. If I do have problems with the aperture blades sticking at a later date (not now, while everything's working), what solvent should I use to de-oil them? Should I also degrease and regrease the focusing mechanism (where I presume the oil came from)?

[cooltouch]

I wouldn't mess with the focusing mechanism unless its showing signs of stiffness. If it feels loose, you might want to, but I personally don't mind a somewhat loose feeling focusing helical.

As for cleaning the blades, you can use lighter fluid, or naphtha.