Planning to send my Mamiya lens in for haze removal

[flavio81]

Haha! Me too, but I'm not sure how quick that will happen. Most of my photo activities have been on hold for the last several months and I still have 7 rolls of 35mm film to print from a late 2019 photo expedition to Italy. I also have two other cameras that are waiting their turn to go on their first local photo expedition. For now, I will probably just shoot a test roll to make sure everything works okay and that the lens is as sharp as it used to be (ie: that I didn't screw it up taking it apart).

Lens will be just fine.

So, the heat treatment is only 30 minutes? Only one heat treatment in the end, or would you recommend two?

Also, why did you put the glass into a preheated oven? Doesn't this increase the chance of the lens breaking up? I thought starting with a cold oven would be safer.

 

[Dave Krueger]

Lens will be just fine.

So, the heat treatment is only 30 minutes? Only one heat treatment in the end, or would you recommend two?

Also, why did you put the glass into a preheated oven? Doesn't this increase the chance of the lens breaking up? I thought starting with a cold oven would be safer.

I simply based the procedure on what shutterfinger outlined in post #40 of this thread. I don't think it would matter if you put the lens in the oven before preheating it, but I did notice that the preheating raised the temperature higher than the preset value. The temperature near the lens position at the end of the preheat phase (before opening the oven door) was 392F when I did the front pair. For the rear pair it was 377F. The oven may overshoot during preheat knowing that a lot of heat will be lost when the door is opened to place food inside. I'm just guessing, though.

The reason for doing three cycles was again based on post #40 which also says that the three cycles should be repeated if the lens doesn't clear after a few days. I think there is variation between ovens, so it's possible that the number of cycles may vary depending on the oven. I suspect my oven got slightly hotter when I did the front pair, resulting in quicker clearing, but higher temps probably risk damaging the lens, so more cycles at less risky temps is better than fewer cycles at higher temps.

I checked the lens after each cool-down phase. For the front pair, the lens cleared after a single cycle so I stopped. I'm not sure if there would be any benefit to repeating additional cycles after it clears. Also, I think clearing continues after it cools down. After the third cycle on the first pair, the lens looked a lot better, but it seemed to become even more clear over the next several hours. I kept looking at it. I was having trouble believing my own eyes.

I didn't worry a lot about details because I trusted shutterfinger's suggestions and felt I didn't have anything to lose since the lens was useless as it was.

 

[shutterfinger]

SK Grimes had an article on lens recementing. In it they showed putting the elements on a hot plate at 425°F. Fast high heat may crack the elements or warp the mount barrel.
Preheating the oven minimumizes the time the lens is in direct heat from either the flame in a gas stove or the element in an electric oven.
The lower temperature is safer to both the element and the mount barrel.
One is only trying to soften the Balsum so that it recures, not melt it off.
An oven that heat to 375°F to 400°F on inital heating has a bad thermocouple that reads inaccurately when cold.

 

[Dave Krueger]

I spoke too soon. The lenses did clear, but the front pair (the pair that cleared more quickly) is more clear than the rear pair. If I shine a flashlight through it at an angle, the collar casts a shadow across the glass on the rear lens. It doesn't do that on the front lens. In other words, the flashlight is still illuminating the glass with a bluish color. I hadn't compared them before because I didn't have them out of the lens barrel at the same time. So, while the rear elements are much better than before, they are not "like new" as the front pair appears to be. The reason I discovered this is because I noticed that the viewing screen image was not as contrasty with the 127mm lens as it is with the 50mm lens which has never had any haze (so far) even though both lenses were purchased on the same day. The only difference between the two is that the 127mm was always attached to the camera when not being used while the 50mm was stored in the same case, except with lens caps on each end.

So, I am now running through a second set of three oven treatments. The rear lens pair s also the one that I boiled, but I don't know why that would have any effect on how the lens reacts to the oven treatments. This makes me want to buy a few cloudy RB-67 lenses from ebay and do some more experimenting. LOL!

 

[Dave Krueger]

SK Grimes had an article on lens recementing. In it they showed putting the elements on a hot plate at 425°F. Fast high heat may crack the elements or warp the mount barrel.
Preheating the oven minimumizes the time the lens is in direct heat from either the flame in a gas stove or the element in an electric oven.
The lower temperature is safer to both the element and the mount barrel.
One is only trying to soften the Balsum so that it recures, not melt it off.
An oven that heat to 375°F to 400°F on inital heating has a bad thermocouple that reads inaccurately when cold.

Well, I apparently still have some residual haze on the rear pair. I tried to find the SK Grimes article, but they apparently took it down. I hear what you're saying, but I'm tempted to rerun the rear pair with the temp a little hotter because the front pair cleared better than the rear pair and the only difference that I noticed was that the oven temp got a little higher with the front pair. In any case, now that I've cycled the rear pair again at 325F, I am going to let the lens sit for a while before doing anything more to it.

I must say, the lens looks amazingly clear compared to the milky haze it had previously. It's hard to imagine how it could be lowering the contrast when it looks that clear. Maybe I'm being overly sensitive. I'll give it some time and then shoot some pictures through the 127mm and 50mm lenses to see how much of a difference in contrast there is on the film.

 

[Kino]

You might want to declare victory on this lens and try another! I can't imagine constant temperature cycling won't eventually cause some problem that won't be repairable with even more heat.

Maybe the elements initially need an extended period of high temperature?

Maybe you only get so many chances to affect the change before the cement is permanently altered? Who knows?

It's possible that some lens elements might not ever clear totally, but it sounds like you've made a major improvement.

 

[Dave Krueger]

You might want to declare victory on this lens and try another! I can't imagine constant temperature cycling won't eventually cause some problem that won't be repairable with even more heat.

Maybe the elements initially need an extended period of high temperature?

Maybe you only get so many chances to affect the change before the cement is permanently altered? Who knows?

It's possible that some lens elements might not ever clear totally, but it sounds like you've made a major improvement.

I agree. I think it's fair to say that the oven treatment resulted in a stunning reduction in the haze, but my belief that it the haze was eliminated completely was not accurate. It's possible that a longer heating cycle or higher heat might further reduce the haze, but it could also reverse the gains. For example, maybe the repeated heating process causes the old balsam to attack or etch the surface of the glass. I would have to run many more experiments on many more samples to answer these questions and I won't be doing that.

When I take some pictures through this lens, I will post the results, probably by comparing it with the 50mm lens (keeping other variables constant).

 

[Kino]

Sheer speculation on my part, but maybe the haze is out-gassing of something (residual solvent?) in the Balsam and the heat allows the cement to become malleable enough for the gas to escape. It might be that the temp has to be held for a longer time in order for the gas to entirely exit the join.

But then again, I only speculate...

Good job!

 

[Dave Krueger]

Shear speculation on my part, but maybe the haze is out-gassing of something (residual solvent?) in the Balsam and the heat allows the cement to become malleable enough for the gas to escape. It might be that the temp has to be held for a longer time in order for the gas to entirely exit the join.

But then again, I only speculate...

Good job!

Thank you.

Maybe shutterfinger could shed some light on the preference for several repeated shorter cycles versus one long one. I am not opposed to a single extended heating cycle. It's true that the lens is much better now than it was, but there would be some benefit to exploring how much margin we have in this process even if it risks reversing the current gains.

 

[MattKing]

If the haze is light and consistent, you may have the perfect lens for portraits and high subject luminence range scenes!

 

[shutterfinger]

The only lens I heat treated was a 12 inch f6.3 Goerz Dagor in a Compound shutter. It did not clear initialy. i had a gas stove at the time, heated the oven, put the lens cell in the center of the oven, turned the oven off, waited until it cooled then repeated the next day. I gave up on the lens and put it away. 3 or 4 months later I took it out and to my surprize it was crystal clear.

Dave are you compairing Fuji Apples to Fuji Apples with regard to the contrast of the 50mm and 127mm? Newer lens have better(?) coatings that produce higher contrast without a change in optical design or lens label.

 

[Dave Krueger]

If the haze is light and consistent, you may have the perfect lens for portraits and high subject luminence range scenes!

I don't really do portraits, but it did occur to me that this lens could be useful for nighttime small city shooting (street corners, etc) . Sort of like an automatic means of preflashing the film. I'm doing some outdoor and indoor test shots now. I can say that shooting into the sun exacerbates the problem as expected. City lights would likely do the same, but I am curious about what it would look like anyway.

 

[Dave Krueger]

The only lens I heat treated was a 12 inch f6.3 Goerz Dagor in a Compound shutter. It did not clear initialy. i had a gas stove at the time, heated the oven, put the lens cell in the center of the oven, turned the oven off, waited until it cooled then repeated the next day. I gave up on the lens and put it away. 3 or 4 months later I took it out and to my surprize it was crystal clear.

Dave are you compairing Fuji Apples to Fuji Apples with regard to the contrast of the 50mm and 127mm? Newer lens have better(?) coatings that produce higher contrast without a change in optical design or lens label.

The 127mm and 50mm were both bought new on the same day (1990-ish) and are both Mamiya-Sekor C lenses.

All I can say is that the improvement from the heat treatment was stunning, but the much reduced residual haze is still problematic. The RB is a heavy monster, so I haven't been using it much, but it still looks like new, so this is a disappointment. In any case, I will check the lens again after some weeks or months and see if there is any change. If not, I may try a longer treatment or a higher temp.

 

[shutterfinger]

The RB is a heavy monster

That's why I switched to 4x5.

 

[Brusselsbased]

It was a great pleasure to find this thread as I’m facing the same problem. Recently got my Rb67 pro sd with 127mm k/l lens, was posted as tested and in good condition, visually and mechanically was true, however after few test rolls I’ve noticed highlights flaring and general softness of the lens uncharacteristic of mamiya glass.

Long story short after digging further and eventually ending up with a rare double in the oven, I have the same issue as the author.

the only difference after one cycle in the oven at 160 degrees Celsius, which is about 325f as suggested in earlier posts, the fungus like growth has appeared all through out the double and I mean a really tree looking growth, plus some separation on one side.

does anyone know should I run more cycles at this point? Also no fungus was noticeable before just the same old foggy/hazy cemented element.

also doing some research I’ve found that fungus would die at about 130f which is almost half of the temperature that I set, however somehow it resulted in it developing out of nowhere?

hope someone can help.

 

[shutterfinger]

I would clean the elements with Isopropyl Alcohol or Hydrogen Peroxide then set in direct sunlight for a day or two.
You may have to separate the pair, remove the old cement then recement them. If the glass is etched it will remain.

 

[reddesert]

I don't think that's fungus. You might be decementing the lens elements by heating them - not sure if that was the goal of this exercise.

 

[Dani]

The 127mm and 50mm were both bought new on the same day (1990-ish) and are both Mamiya-Sekor C lenses.

All I can say is that the improvement from the heat treatment was stunning, but the much reduced residual haze is still problematic. The RB is a heavy monster, so I haven't been using it much, but it still looks like new, so this is a disappointment. In any case, I will check the lens again after some weeks or months and see if there is any change. If not, I may try a longer treatment or a higher temp.

How are the lenses now? I'm curious how they are looking after a couple of years have gone by.

 

[John Earley]

I'll bump this thread too as I'm interested in any new info on this subject.

 

[eli griggs]

I watched the video again and he was using acetone to dissolve the thread locker, as you suggested. He was cleaning the lenses with hydrogen peroxide and lighter fluid (not at the same time, of course). From the videos, it looks like the front and rear lens groups can be removed from Mamiya lenses without much disassembly of the lens body. Since the shutter works fine, I am now seriously considering doing the job myself and have looked up the tools in Amazon. If there are problems with glued element, I'll cross that bridge when I get there.

When y'all are speaking of lighter fluids, are you specifically talking about Naphtha or one of the new formulations?