Cleaning HAZE in Mamiya 80mm F1.9 N cemented rear element

[Huss]

There's a lot of info out there on that there internet. At least some of it is good.

what if it directs me back here?

 

[ags2mikon]

I did a 13.5cm Nikkor Q (tessar formula) in Bronica mount that had separation in the rear group. I put a trivet in a pan of distilled water and very slowly heated the water while the lens group was sitting on the trivet.
After about an hour of sub boiling 195-205 degrees it fell apart in the pan. I allowed it to cool slowly and cleaned it with acetone and used UV curing cement and a set of v blocks to center the glass and turned on the uv lamp. I'm still using the lens 25 years later. Was it worth it? The lens was a freebie because of the separation and the wife was out of town and didn't know what I was doing with her pans so I think I did okay. The lens seems okay and makes nice pictures but I don't have an un-molested version to compare it with. YMMV.

 

[NB23]

Excellent!

I did a 13.5cm Nikkor Q (tessar formula) in Bronica mount that had separation in the rear group. I put a trivet in a pan of distilled water and very slowly heated the water while the lens group was sitting on the trivet.
After about an hour of sub boiling 195-205 degrees it fell apart in the pan. I allowed it to cool slowly and cleaned it with acetone and used UV curing cement and a set of v blocks to center the glass and turned on the uv lamp. I'm still using the lens 25 years later. Was it worth it? The lens was a freebie because of the separation and the wife was out of town and didn't know what I was doing with her pans so I think I did okay. The lens seems okay and makes nice pictures but I don't have an un-molested version to compare it with. YMMV.

 

[reddesert]

I think if someone's going to say de-cementing a lens is simple, it's fair to ask them to provide details.

I haven't done this myself but I have done a little research. If a lens is cemented with balsam, I believe slow heating at boiling water temps will eventually release the glue. But if it's cemented with modern UV cured optical cement, that is unlikely to do anything.

Makers of optical cements also sell solvents for de-cementing, or a few give some information on usable solvents. The solvent typically named is methylene chloride. This is nasty stuff. Not kitchen material. You should be prepared to work in a fume hood and wear a respirator, IMO.

Norland, one of the main manufacturers of optical cements, gives this information: https://www.norlandprod.com/techrpts/separating.html (It is somewhat out of date as I don't think you can buy methylene chloride paint stripper in the US any more.) BTW, their alternative is hot mineral oil at 400 F, try explaining that to the spouse.

Naturally, if you start decementing a lens, you have to take the process all the way or you just have a lens with crazing between the elements.

 

[ags2mikon]

You can still buy methylene chloride from lab supply houses. You don't need very much. I don't think I would do it in the kitchen while the wife is out. No no no. Go outdoors with good ventilation. Methylene chloride was in all the carb cleaners / parts dip that was sold in auto parts stores years ago. I think that it was used as film cleaner too. Wear good PPE and go outside and melt lens cement.

 

[lxdude]

what if it directs me back here?

Well, then you're going to have to insist on just good advice!

 

[Qiuhong]

I think we're talking about different things, this group with haze is not 2 lenses attached together in the middle, they're not touching each other but held by the black metal ring, only the edge of these 2 lenses are glued to the metal ring and it's hollow inside. So the method you're suggesting doesn't apply to this group. But thanks for the advice anyways

separate both lenses, clean them. Then, glue them together with a tiny drop of cement right in the center (canada balsam or any lens glue) and squeeze both elements together. The glue will spread and cover completely.
Cure with UV or with time, depending on which glue you have used.

Be as accurate as possible, centering both lenses. It’s not difficult.

 

[NB23]

Ok, I guess the question is how do you separate the glued lenses. What tools so nothing gets damaged? And then how do you clean the old glue off the previously cemented pieces? A solvent? What kind? Would any mechanical cleaning be involved?
Curious because I sold that lens fully disclosed as being hazed (whatever you want to call it, looking at it, it was hazed) and so suitable for soft contrast shots. It could have been interesting to take a crack at it. But also it was interesting that no repair shop I contacted wanted to touch it. Which, according to your instructions, seems odd if it was as simple as you make it out to be.

No shops want to do it because of risk.

But the main reason is because repirmen only want to use a Chiffon for a quick cleaning and look like heroes.

Skyllaney is your best bet. Those guys are impressive. Find them on ig.

 

[NB23]

I think we're talking about different things, this group with haze is not 2 lenses attached together in the middle, they're not touching each other but held by the black metal ring, only the edge of these 2 lenses are glued to the metal ring and it's hollow inside. So the method you're suggesting doesn't apply to this group. But thanks for the advice anyways

If so was the case, none of the repair people would refuse the job.

If I read you correctly, your lens Is basically a Chiffon + alcohol job.

 

[ags2mikon]

The first post said cemented rear group. The op's last post states it is air spaced but cemented to the barrel. I haven't seen anything like that before. Its a shame too because the 80mm f 1.9 is a great lens.

 

[Oldwino]

Skyllaney is your best bet. Those guys are impressive. Find them on ig.

It would be cheaper to buy another lens.

 

[Huss]

It would be cheaper to buy another lens.

I would not buy the 80 1.9 though. The one I had was in perfect shape when I bought it. I kept it in a dry box when not in use - like all my gear - and lo and behold, one day when I wanted to use it, it was now hazed. This lens is notorious for that so the best advice is to stay away from it.

 

[Qiuhong]

I would not buy the 80 1.9 though. The one I had was in perfect shape when I bought it. I kept it in a dry box when not in use - like all my gear - and lo and behold, one day when I wanted to use it, it was now hazed. This lens is notorious for that so the best advice is to stay away from it.

interesting..... I would expect better quality in mamiya products....

 

[awty]

Haze is a common problem through out all aging lenses from many manufacturers, some models are worse than others.
Best do research before buying. None of my Mamiya lenses have haze and they are excellent lenses.

 

[Qiuhong]

Haze is a common problem through out all aging lenses from many manufacturers, some models are worse than others.
Best do research before buying. None of my Mamiya lenses have haze and they are excellent lenses.

I realize that, i have 80 2.8 and 55 2.8 and they're all crystal clear,

The first post said cemented rear group. The op's last post states it is air spaced but cemented to the barrel. I haven't seen anything like that before. Its a shame too because the 80mm f 1.9 is a great lens.

Maybe I used the wrong term, what I meant was the lens was cemented on the edge not to each other, I also did a sketch (bad one)

 

[MattKing]

interesting..... I would expect better quality in mamiya products....

In order to achieve 80mm f/1.9 and coverage for 6x4.5, with then available materials, some very interesting optical design choices had to be made. Sometimes those design choices mean a lens is more prone to age related deterioration than other lenses.
Your lens could be more than 1/3 of a century old, and could have been heavily used.

 

[abruzzi]

FYI, the 1.9/80, definitley looks like a "Planar" design to me, and there is one pair that are cemented, but from the OP, I assume that is not where the haze is:

 

[MattKing]

That is a much older, "C" version of the lens.
But optically speaking, the N version looks very, very similar :

 

[NB23]

I have noticed the Summicron 50mm V4 to be very prone to an element hazing. I’ve had three with the same problem, including a boutique black paint classique V4 not used much at all.

I guess it’s the grease outgassing. Luckily, it cleans easily.

 

[Huss]

interesting..... I would expect better quality in mamiya products....

It is the only one that does it. All my other Mamiya lenses have been great with zero issues.

 

[Oldwino]

My understanding is that the 35mm Sekor is also prone to haze issues.

 

[drfoxmd]

There's a lot of info out there on that there internet. At least some of it is good.

If you are not skilled in lens disassembly and reassembly you are better off selling to a skilled lens repair person and finding another lens without haze/separation.

 

[flavio81]

That is a much older, "C" version of the lens.
But optically speaking, the N version looks very, very similar :
View attachment 323142

The haze is most likely on the cemented element. This is typical of many lenses.

For example the Pentax-M and Pentax -A 50/1.4 lenses suffer of the same problem, also at the rearmost back group. As well as the famous Super-Multi-Coated Takumar 6x7 105/2.4; many many of them suffer from haze. The same cemented group (in terms of position) also suffers from haze on many FD 50/1.4 SSC and New FD 50/1.4 lenses. And the list goes on and on.

But, also, lens elements that are next to the iris might also show haze due to evaporation of some contaminants (oil etc). Those are easy to clean since the haze isn't inside lens cement.

In this case the cemented group is also next to the iris, so a disassembly is needed to check what's going on. However, from the supplied picture, to me it definitely looks like haze at the cemented surfaces.