Micro-Nikkor 55/2.8 sticky aperture

[GeneW]

I wonder if you folks here could give me some advice. I have an AIS Micro-Nikkor 55/2.8 lens that started developing a sticky aperture some while back. Now it will only close down to about f/4. The lens was given to me about three years ago and it's one of my faves. I'd like to get it working again.

What causes a lens aperture to stick? Crud? Lack of lubricant? I don't see any sign of oil on the blades.

Is it a tricky repair? I'm not a good DIY person so I'm a bit reluctant to mess around -- should I just take it in to a repair person?

Gene

[herron]

Gene:
Although I haven't tackled the task lately, I've cleaned and reassembled a few lenses in my day (Walker just finished doing that one with 15 iris blades!) It never struck me as hard to do...just tedious, and something you have to be careful with sometimes. Good eyes (or a large magnifying lamp), and steady hands help, too.

If, like Walker's example, some of the blades are dislocated, you are going to have to disassemble it to get to the iris blades...and repositioning them is one of the tedious & careful things I mentioned. But sometimes it doesn't take a total disassembly to get things working well again. From what you described, I don't think you need to go that far.

The blades can stick for a lot of reasons, and it really doesn't take much for them to do it. I would avoid putting lubricant on the iris blades. I have occasionally used dry graphite, but I really don't like doing that, either.

I've had success a few times by simply cleaning the iris with lighter fluid - yeah, plain old Rosinol lighter fluid! I would remove the front and rear lens elements (be careful of which side is which, when you remove any of the glass, so it goes back in the same way). Over a tray, in a well-ventilated area, I would pour the lighter fluid over the blades, exercising the lens to distribute it (by the way, I hope it goes without saying to avoid sparks and open flame).

You may have to repeat the process several times, to be sure any "gunk" (technical term ) is dissolved and removed. When the blades are moving freely again, let the whole thing sit for a while, so the lighter fluid will evaporate, before you reassemble.



-----
Of course, if you have a good repair person about, you can always go that route and save yourself the grief and tension...not to mention the purchase of some adequate jeweler's screwdrivers for removing some of the miniscule screws holding things together....

[PeterW]

I agree with everything you said, Ron - for most prime lenses.

Although I haven't tackled the task lately, I've cleaned and reassembled a few lenses in my day (Walker just finished doing that one with 15 iris blades!) It never struck me as hard to do...just tedious, and something you have to be careful with sometimes. Good eyes (or a large magnifying lamp), and steady hands help, too.

I would sound a warning though about some prime lenses where removing the front and rear elements doesn't take all the glass out. On a few there's a separate central group, and if you use Ronsonol on the iris blades without taking it out you're certain to get some gunk washed on to this glass, and its not all that easy to clean it off with a Q-tip.

One other point is about zoom lenses. Avoid taking them apart until you've tacked a few prime lenses because zooms can be P-I-Gs to put together and get the focus right at both ends of the zoom range.

The worst one I've tacked was a Canon f/4 80-200 (15 elements in 11 groups) which a friend had dropped in the river in about three feet of water and gone paddling in mid-winter to retrieve. He brought it round to me in a plastic bag and said: 'Can you have a go at it, please. If you bugger it up it doesn't matter because it's useless as it is full of river water.' I was dubious, but said I'd have a go.

Taking it apart and cleaning was easy. But it took me about four evenings of trial and error to get it all back together again and focusing properly. I came very close to throwing it in the bin! He insisted on taking me out for a really nice meal, but its not a job I want to tackle again in a hurry.

PeterW

[doubs43]

Gene, the most common problem in my limited experience is oil on the blades. When I opened the Orestegor, the 13 blades that hadn't come loose came out as a perfect circle of stuck-together blades! Oil that had stiffened was the culprit and a good soaking in isopropal alcohol, separation of the blades and then wiping each one solved the problem. Hint: some blades, like my Orestegor, are not symetrical so take note of how they are oriented.

Another lens I had to take apart because of oil on the blades was a CZJ 180mm Sonnar. The blades were stuck wide open and until I took it apart I wasn't sure it had blades at all.

Like Peter, I've recently gone into a zoom lens sold by Sears in a Canon mount. One of the rear lens elements was fogged badly and it was about the third lens in a group of about six so being careful of the lens' orientation was important. Also, the iris only worked part time. I used denatured alcohol applied with a syringe to clean things. It only required a couple of small drops but a 50mm f/1.4 Canon FD lens required full disassembly and a thorough flush of the blade assembly - it came out as a unit - twice.

Ron is correct: do not put anything on the blades. Completely clean and dry is best.

If you go for it, work slowly and carefully and you'll be fine. Good luck.

Walker

[herron]

Peter raises a good point. In my haste to answer, I neglected to carry the thought to the extremes. Certainly it should be noted that all glass should be removed when using denatured alcohol or lighter fluid as a solvent...and this can be a bit trickier when there are central elements to consider.

If you are fortunate enough not to have to disassemble much, loosening the dried oil that may be hindering your aperture blades can be a quick fix. But sometimes, as Peter and Walker noted, it isn't...and you must take things totally apart...and those blades are notoriously thin and easy to bend (particularly for a moose like me)...plus you need to avoid leaving much oil residue from your fingers, too...all of which is also why I added that note about "grief and tension" -- because it can certainly do that to you!

[casualcollector]

I'll add to the above cautions. If you remove the iris unit, scribe a mark to get it back in the proper orientation and keep the f-stops calibrated. I successfully cleaned the unit in a Kiron 28mm that had gone swimming but have no idea how to get the aperture re-calibrated!

As an aside, The Kiron was a Canon FD mount with the attendant bazillion itty bitty ball bearings in the back of the mount. The swim seems to have locked the races up, solid. A week long soaking in PB Blaster (for freeing rusted parts) had no effect. Anyone hae a suggestion?

[PeterW]

I'll add one further note of warning about cleaning iris blades, and shutter blades.

If you're dealing with antique lenses and shutters be very careful what cleaning fluid you use. Some shutters, like the Unicum and, I believe, some shutters on older Graflex cameras, had iris and shutter blades that were made from thin vulcanite.

I don't know what, if any, effect a soaking in Ronsonol lighter fluid (naptha) or any other cleaning solvent has on this, but I've never chanced it. Also, apart from any possible chemical damage, old thin vulcanite is VERY brittle so go easy lifting them out and putting them back.

Even more liable to damage, chemical and physical, were the shutter blades on early Compound shutters (ancestors of the Compur). They were made from hot-rolled impregnated black paper - honest! If you get most cleaning solvents on them they crumple and go limp!

Use ONLY a dry cloth on parts like this.

PeterW

[Reiska]

I hope, that you don't mind my writing here. Perhaps the answers to my question could be useful for Gene too.
I posted some days ago, that I am a lucky winner of really nice Fujica gear. The only dark cloud in front of my
euphoria is, that the 50/1,4 Fujinon lens has a sticky aperture and "a pale shade of fungus" I have a decent
spanner wrench etc. but I would like to know how you keep the lens steady when you use the tools?

Only the 50mm lens is imperfect.

[herron]

Nice looking outfit, Reijo!

I use a PanaVise to hold camera bodies and lenses when I work on them. Works very well. Got it from Micro-Tools. They have a USA and European site.

[vintageslrs]

Ron

That looks like an excellent tool.....someday if I'm ever flush again...I would like one!

thanks for the info.
Bob

[Reiska]

Thanks, Ron

Like Bob hinted you can't get it with buttons. The price here is €122.90 + shipping which is about 17 Euros !! You gave me a good advise.
Now I know at least what I have to look after. I have an old bench vise and after some adjustments it might be usable. I mean by using some
concave and rather stiff piece of cellular rubber softening between the chins I will get it more lens friendly.

[herron]

vintageslrs said:

Ron

That looks like an excellent tool.....someday if I'm ever flush again...I would like one!

thanks for the info.
Bob

I bought it years ago...by pretending I didn't see that Mamiya rangefinder on eBay that I wanted (even though I already had one).......price has gone up about 10% since I bought mine. Believe me, it works great. If I had it to do over again, I would skip lunches for a while....of course, at my size I could afford to skip a few dinners, too.

[GeneW]

Thanks for all the tips, and cautions. You've convinced me to take the lens downtown to one of the good repair shops and get an estimate. Let me put it this way -- when I worked in IT my forte was software :-)

Gene

[herron]

Gene:
I didn't want to come right out and dash your hopes of repairing it yourself. It can be done. But I've taken to trundling off to a favorite repair shop instead, for most intricate things. My hands can palm a basketball, but tiny little springs and delicate iris blades make my eyebrows sweat.

Plus, my eyes get tired a lot faster than they used to.....(sigh)