NIKON PlanApo 100X/140 oil that is a PlanApo 60X/140 oil

[apochronaut]

Apologies. I haven't looked at this for a bit.
Usually with that style of objective, there is a removeable shroud that carries the specs. Once removed a travel guide or channel is revealed, with a small brass stop screw running in it. That screw is turned into the inner objective casing, stopping it from moving too far north or south.
Removing that screw, will allow the inner casing to slide out. There may be a further threaded collar under the shroud, towards the lower end. When it is removed as well as the screw, the objective casing will likely come out the front.
When oil has invaded an objective , it usually has been used too liberally and or the objective has been continuously left sitting immersed when not in use. It can get everywhere over time and will gum up and seize threads. That shroud is most likely just tight. It will be a standard right hand thread. Most will come free with a good hand grip, but if not try a bit of solvent at the junction between it and it's neighbour ring. Take a magnifier and look for the seam. Leave the solvent for about an hour, after it gets into the seam.
Persuasion may be necessary, after all. I use two leather straps, each wrapped around a counter revolutionary part and gently clamped with small curved jaw vice grips. The 6" are great but I've used 10 too. Clamp them loose and incrementally tighten them a bit at a time until they just don't slip. One can go on the grip ring if it is not part of the shrould, which I doubt it is. Those flat dense rubber bungie straps work pretty well too. I even used those wide brocolli elastics, 3 deep once when I broke an objective down at someone's house years ago. You don't want to crush the shrould, so gripping it high or low is best. It is weakest in the middle. They are usually quite strong, but gripping just at the taper where the metal is thicker or right on the internal thread at the top are the strongest areas.. Once it has turned a little, your fingers should do the rest but remove the vice grips first, since they can slightly spring the thread of the shroud, making it a bit tight until the pressure is off.

[stjepo]

Apochronaut, you are very generous in sharing your knowledge. Here is the result of your instructions. After protecting the "upper" and the "lower" side of the objective like an " egypcian mummy"and using my "special tools" I managed to open and separate its shroud that as you say "there is a removeable shroud that carries the specs." Thank you

"The Mummy":

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Opening of "The Mummy"

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Revealed content:

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More to be seen:

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Apronaut's help is priceless.


Thank you Chas for the link to that Italian page, I had seen it before but as you say there were only two diferent Nikon Objectives.


To be continued...

[apochronaut]

That grayish coloured collar should come off and allow the barrel to come out once you have removed the locating/guide screw. Don't forget to put the thermostat back in your car.

[stjepo]

Stuck again, soaking with small drops of xylenol. The ring does not rotate.

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Next to come...

[apochronaut]

lockscrew?

[apochronaut]

The only comparable objectives I have on hand are a set of Nikon glycerin immersion objectives from the era of your objective. Nikon didn't use a consistent method of applying that lower ring.
Usually it is a bit snug and as in the case of your shroud, might be very snug, so might need some persuasion. On one of my objectives, that ring is physicslly attached to the shroud and both the ring and shroud go on and off on a single thread, which is internal to the ring.

None of mine have holes in them but yours looks to have a hole. Is there a locking set screw in there or is that the travel limit screw.

All of the Nikon objectives I have described a bit, have the travel limit/guide screw external. Once the shroud is removed , you can see the screw going up and down in it's channel as the objective nose is depressed and released. In that system, the head of the screw is the functional part. It is also possible to use the tip of the screw as the functional part. Only the head would be visible under the shroud, and the channel would be cut into the inner barrel, rather than the outer.

[stjepo]

As you said, the ring was very tight, even tighter than the shroud, and it took a lot of persuasion.

APERTURA SEGUNDO ANILLO.jpg (68.63 KiB) Viewed 2016 times

I had previously removed a small travel limit screw.

Now I'm looking to see if there are any external marks.

[apochronaut]

The guide screw will locate the inner barrel in the outer barrel. It is the alignment of the lens stack with the inner barrel that is important.

I suspect on that objective, that the front cap ring is integrated with the barrel. On some it is a separate thread on ring , which allows for separating the front and second cell, without disturbing the centered second cell but even though it looks to be on yours, I doubt it is.
The second cell has centering plugs.
Often you can drive the lens pack out without disturbing the centering but sometimes not. Unfortunately, you have a euchered objective, and your only option is to fix it.

A ballpoint pen cap with the pocket clip pared off makes an acceptable soft punch, with which to drive the lens stack out of the barrel.

[stjepo]

Apochronaut,I managed to get the barrel in order, marked the order and alignment (I hope I did it right).I found two shims at the top

The front lens is stuck to the barrel and I managed to clean it but I'm afraid that there is a tiny lens (like a contact lens) in the center that does not allow a tiny bubble in its center to come out. It was full of oil, Isopropyl alcohol was used to clean it.

I suspect that this lens, which came with Labophot, already came with that problem and I don't know if I will be able to rescue it.

I will continue trying to clean it and remove the bubble and if I succeed I will seal the lens since the top part is where the oil penetrates.

I don't think he will be saved.

Thanks again for your kind help

[apochronaut]

This tiny lens you speak of. Is it mounted in the front cell, immediately behind the front lens?

[PeteM]

Removing the front element(s) is often the most difficult part. Sometimes a "lens sucker" can help if the lens isn't cement or stuck in place.

Since the objective is likely a goner anyway, you could also try further loosening the seal at the front and then pushing it out through the tube. That could allow you to separate and clean the elements - and re-cement if needed.

Sometimes, there are three tiny holes from the side of the objective casing, filled with a sort of elastomeric compound to secure the front elements. If so, you might have to dig those out.

I've thought of using an ultrasonic cleaner in cases like this, but never had the courage (or perhaps stupidity) to give it a try as a last resort.

[apochronaut]

I think, Pete he is talking about an internal leak in the front cell. Not between cells, as you are describing. For those reading this from the outside : objectives are made up of discrete lens assemblies which are assembled in a stack. Each assembly is usually a sealed homogeneous unit, separated on shoulders or also with shims from the others in the stack. Oil usually enters and coats front and aft surfaces between cells but it can enter a cell too. This is rarer.

With some objectives, the front cell contains only the plano/convex N.A. determining lens. The meniscus lens is in the next cell. Others include the meniscus lens in the front cell.
My question was to clarify whether there is an oil leak between the front lens and the next lens in the front cell.

[stjepo]

This tiny lens you speak of. Is it mounted in the front cell, immediately behind the front lens?

Yes, mounted in the front cell, immediately behind the front lens

[apochronaut]

Unfortunately. I guess, keep your eyes peeled for an identical twin with a different problem.

[stjepo]

Removing the front element(s) is often the most difficult part. Sometimes a "lens sucker" can help if the lens isn't cement or stuck in place.

Since the objective is likely a goner anyway, you could also try further loosening the seal at the front and then pushing it out through the tube. That could allow you to separate and clean the elements - and re-cement if needed.

Sometimes, there are three tiny holes from the side of the objective casing, filled with a sort of elastomeric compound to secure the front elements. If so, you might have to dig those out.

I've thought of using an ultrasonic cleaner in cases like this, but never had the courage (or perhaps stupidity) to give it a try as a last resort.

"try further loosening the seal at the front and then pushing it out through the tube. That could allow you to separate and clean the elements - and re-cement if needed." I'm afraid to do it, but as you say "I've thought of using an ultrasonic cleaner in cases like this, but never had the courage (or perhaps stupidity) to give it a try as a last resort." I am your man, stupid enough to do so "Since the objective is likely a goner anyway". I'm in the middle of an ultrasonic cleaning. First I used a mixture of 14% isopropyl, 70% distilled water, Fairy 2%, ammonia 14%. Now I'm in the second stage of using only pure isopropyl and praying to the lens Gods that it works, although I have little hope.

[stjepo]

Unfortunately. I guess, keep your eyes peeled for an identical twin with a different problem.

Is there another identical lens?

[stjepo]

Yes, there are two lenses one above the other at a distance that gives the sensation of being a small transparent cylinder.

[apochronaut]

I meant , another twin objective with a different problem.
The front element is a press fit into a shallow cylinder with a lip at the bottom or is a kind of circular rabbet joint, if the maximum o.d. of the lens exceeds the diameter of the exposed plane surface. The brass surround of the barrel to the rear of the lens is furled around the edge of the hemisphere of the back lens surface. The fit of the lens in it's machined basket is what seals the oil out. In most objectives the next lens, which is usually a meniscus lens, is the front lens of the next cell : the cell that is centered against the front lens.

I have seen some that build the meniscus lens into the front cell with an air space between. If this is the type you have, then the oil can only get into that space in one of two ways. The first and most likely is by seeping between the front lens and it's mounting surface(s) under the small amount of pressure exerted on it during dipping, or it bypassed the bezel seal( white) over many episodes of too much oil being used , got into the inter cell space between cells one and two and eventually drained into the inter-lens space in cell one by gravity. If there is no oil between cells one and two, then the latter didn't happen.
The question becomes : even if you extract the oil from the inter-lens space of cell one, how do you stop the same leak from repeating and will the objective perform well, afterwards because the front lens could be slightly dislodged ?
One major reason for leakage around the front lens is the effect of pressure on that lens. It can be a big bump, which usually shows or repeated minor hits on the slide that will dislodge the lens enough to cause leakage. That might not readily show.

I was hoping the leakage was at the seal around the bezel.

[PeteM]

I am your man . . .

Hope you let us know if it manages to improve things. Civilization is made with courageous pioneers like you - both what works and what doesn't.

Two thoughts, probably both of which you know. First, make sure the objective barrel is suspended in the cleaner, rather than resting on the bottom where it might get banged around at something like 30KHz. Second, alcohol isn't an especially good solvent for oil. Sometimes a soap can do better.

I'll sometimes put items, along with whatever cleaner or solvent, in a plastic bag and then put that bag in the cleaner. That sometimes makes life a bit easier, especially if you have a large tank.

Good luck!

[apochronaut]

Could be a separated enbedded front lens too. Some companies tried out cement in their earlier offerings and apparently they were not great due to immersion oil acting as a very slow solvent.

[stjepo]

I was hoping the leakage was at the seal around the bezel.

The leak is through the front lens, I see that clearly. When you pour any cleaning liquid on the back it tends to drip through the front lens.

I have also observed:
A) Small particles are released from the edges of the lens where it makes contact with the metal that can be easily observed with a magnifying glass. These particles are very greasy and dirty the front lens;
B) The front lens moves, it is detached from the metal.

[stjepo]

Could be a separated enbedded front lens too. Some companies tried out cement in their earlier offerings and apparently they were not great due to immersion oil acting as a very slow solvent.

That's the feeling I have, it's as if the lens insulator is dissolving because I don't see any dents on the lens that I don't doubt it could have had at some point.

[stjepo]

I am your man . . .

Hope you let us know if it manages to improve things. Civilization is made with courageous pioneers like you - both what works and what doesn't.

Two thoughts, probably both of which you know. First, make sure the objective barrel is suspended in the cleaner, rather than resting on the bottom where it might get banged around at something like 30KHz. Second, alcohol isn't an especially good solvent for oil. Sometimes a soap can do better.

I'll sometimes put items, along with whatever cleaner or solvent, in a plastic bag and then put that bag in the cleaner. That sometimes makes life a bit easier, especially if you have a large tank.

Good luck!

Yes PeteM, I will record my experience with the ultrasonic cleaner. It is true that alcohol does not dissolve oil it spreads it. I think alcohol that should be used only at the end when there are no traces of oil.

The device I use is small, I include the characteristics to keep them in mind.

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Very good idea to put "in a plastic bag and then put that bag in the cleaner"

[apochronaut]

Could be a separated enbedded front lens too. Some companies tried out cement in their earlier offerings and apparently they were not great due to immersion oil acting as a very slow solvent.

That's the feeling I have, it's as if the lens insulator is dissolving because I don't see any dents on the lens that I don't doubt it could have had at some point.

I'm not sure what you mean by lens insulator?

[stjepo]

There's some kind of glue coming off here, that's what I was referring to.

[Hobbyst46]

An interesting thread. Good luck !
BTW, I would not use ammonia to clean brass metal parts.

[apochronaut]

"There's some kind of glue coming off here, that's what I was referring to"

That is most likely hardened immersion oil. There shouldn't be any glue there unless the front lens got loose and someone tried to glue it into place with suction or perhaps magic.. Sloppy microscopists often leave residue around the perimeter of the front lens when cleaning it, which hardens into a sort of stiff goop that can be miserable to get out of it's lair. It is hard to tell from the photo but I wonder if the front lens is depressed below the level of the front bezel an unnusual amount?

An embedded lens is a very small plano/convex precision ground lens of a different refractive index than the actual front lens, embedded into a precision concave relief to make a front doublet instead of the traditional single plano/convex lens. It is very hard to tell if a front lens is embedded but the practice was very common when your objective was made, especially in the advanced wide field designs. Cemented types were used for a while by some companies. If it was a failed cemented type, the cement wouldn't be visible from the outside but it could cause enough separation of the doublet to allow oil to seep in between.
Can you provide a closeup picture of the back of that front lens, or is it back together now?

[stjepo]

An interesting thread. Good luck !
BTW, I would not use ammonia to clean brass metal parts.

True, but helps to clean the lens and is diluted no more than 5%, Thanks

[stjepo]

"That is most likely hardened immersion oil." So there was a lot of oil inside.

"It is hard to tell from the photo but I wonder if the front lens is depressed below the level of the front bezel an unnusual amount?" It doesn't seem like that to be the case if I compare it to others in good condition but I will say like Galileo about the lens "And yet it moves"


"Can you provide a closeup picture of the back of that front lens, or is it back together now?" Of course!!!!

I will try to do my best although now the back is in the process of losing the drops that have condensed after its 'refreshed' bath.

A beautiful drop of water came out of the front lens where the oil that damaged the lens surely entered.

[apochronaut]

I was hoping to get a more descriptiive image of the lens arrangement , not its hitchhikers.
Anyway, you say the front lens moves?
and , am I seeing 3 reflective surfaces in your pictures?