Mamiya K/L Lenses Which Ones Don't Have Haze Issues?

Hi, after a few years away from analog photography, I dug out my Mamiya RB 67 Pro SD only to discover that the K/L 127mm lens has developed lens haze. Since the lens’s longer shutter speeds hadn’t been working properly ever since I bought it used a few years ago, I took the camera to a service center in Vienna that specializes in Mamiya cameras. They managed to repair the shutter successfully, but—as I feared—they couldn’t remove the lens haze.

It appears that this is the well-known issue with the 127mm lens, where fog forms within the doublets. I’ve read here on the forum that special heat treatments can eliminate, or at least significantly reduce, the haze. I might give that a try, though I’d have to take it back to the service center since I’m not confident enough to open the lens myself.

Anyway, what I really wanted to ask is: Do other K/L and L lenses suffer from this problem? If so, which ones? My K/L 65mm and K/L 180mm lenses haven’t developed any haze so far—could this still happen? For future purchases, I’d like to avoid lenses prone to developing these issues. Initially, I’m naturally interested in a K/L 90mm lens as a replacement for the 127mm. In the medium to long term, I’m particularly interested in the Sekor C 50mm; 75mm shift; K/L 140mm macro; K/L 250mm/APO 250mm; and K/L 360mm/APO 350mm. It would be very unfortunate if the same problem reoccurred after a few years as it did with the 127mm.

I have a Mamiya-Sekor C 127mm, 250mm, as well as a Mamiya-Sekor 90mm (from the press series) that all have permanent etching on the inner surface of one of the elements (I forget which now but could go look). The 127 has a reputation for this, but I've never found any conclusive information on what's going on.

aconbere said:

I have a Mamiya-Sekor C 127mm, 250mm, as well as a Mamiya-Sekor 90mm (from the press series) that all have permanent etching on the inner surface of one of the elements (I forget which now but could go look). The 127 has a reputation for this, but I've never found any conclusive information on what's going on.

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Thank you for your answer. Do you mean by "etching" something like a fog, as is often the case with the 127 mm?

FWIW, I expect that one of the reasons there are lots of reports about the haze problem with that lens is that there are probably more of those lenses around than any other lens, and all those used lenses have probably had more use than any other lens.

The vast majority of the 210 and 250 Apo lenses, in both RB and RZ versions, have developed haze in a cemented group by this point. It appears that heat and humidity accelerate the issue, but no guarantees. If you can get the group re-cemented, it should permanently fix the problem. The 50mm C seems to hold up much better, as does the 140 Macro. I think the bigger issue on the 350 Apo is making sure it has the support bracket, most seem to have been separated from their lenses over the years. The 360 (non-apo) is lighter and didn't come with a bracket.

Shutterspeed said:

Thank you for your answer. Do you mean by "etching" something like a fog, as is often the case with the 127 mm?

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Yes exactly. If you touch the lens where the fog is it feels almost like frosted glass.

Not Mamiya, but the Nikon AF 35-70 f/2.8 is notorious for this problem. I had one, paid the Camera Clinic in Melbourne to replace the element at some expense, and a couple of years later the same thing happened., making it useless. Maybe the element is made of a glass that has particular optical characteristics. They gave me the replaced lens and it had a surface like the one described by #aconbere in the post preceding.

john_s said:

Not Mamiya, but the Nikon AF 35-70 f/2.8 is notorious for this problem. I had one, paid the Camera Clinic in Melbourne to replace the element at some expense, and a couple of years later the same thing happened., making it useless. Maybe the element is made of a glass that has particular optical characteristics. They gave me the replaced lens and it had a surface like the one described by #aconbere in the post preceding.

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The theory I keep hearing (probably from posts here!) is that some of lubricants used etch the coating on the lens. But it’s not obvious to me that anyone has done any science on this. I’ve also read that folks have repaired the lenses by having the coating removed. But again haven’t seen anything concrete.

Thanks for your responses!

Hmph, this now sounds rather disheartening if even the expensive APO lenses can develop this haze.

Is it inevitable that every lens sooner or later develops fog, or can we assume that if no haze is present now, none will develop in the future?

What are your experiences with the K/L 90mm? Is it somewhat less susceptible than the 127mm?

I have several 120 year old lenses with no fog, so I'd say no, its not inevitable, or if it is, Its on a longer timeline that I need to care about.

I've seen other Mamiya lenses (M645) develop a haze between doublets. That's a failure of the cement used to bond the elements. I guess Mamiya used a bad type of cement? The effect is much worse than the separation you see in Zeiss (or others) lenses with the iridescent reflections.

Heating the doublet won't resolve the issue. It needs to be separated, cleaned and rebonded while checking the alignment of the elements. To make things worse, some doublets are held in the lens by folded metal and not via a retaining ring. There are some people that can do it for ~USD150 per doublet.

abruzzi said:

I have several 120 year old lenses with no fog, so I'd say no, its not inevitable, or if it is, Its on a longer timeline that I need to care about.

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In my statement I was only referring to the Mamiya K/L lenses.

My Minolta MC lenses are not 120 years old, but they are also older than the K/L lenses and have not developed any haze.

OAPOli said:

Heating the doublet won't resolve the issue. It needs to be separated, cleaned and rebonded while checking the alignment of the elements. To make things worse, some doublets are held in the lens by folded metal and not via a retaining ring. There are some people that can do it for ~USD150 per doublet.

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I don't think $150 is that expensive. However, it will probably be a bit of a hassle to send the lens from Europe to the USA and back again. Do you have any links to the people who can do that?

Photrio member @Nodda Duma did a lens for me (USA)

There is a gent in Taiwan: https://lens-cla.blogspot.com/

And Jaroslav in Ukraine. He's on facebook in the group called "Lens repair - lens repolishing, recementing and MC recoating service"

aconbere said:

The theory I keep hearing (probably from posts here!) is that some of lubricants used etch the coating on the lens. But it’s not obvious to me that anyone has done any science on this. I’ve also read that folks have repaired the lenses by having the coating removed. But again haven’t seen anything concrete.

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Anti-reflection optical coatings typically have thickness of order the wavelength of light - this is an oversimplification for multilayer coatings, but not terribly inaccurate. See https://www.edmundoptics.com/knowle...s/lasers/an-introduction-to-optical-coatings/ for a schematic of what a broadband anti-reflection coating can look like. Anyway, they may be less than a micron thick.

What this means is that if the damage to the lens has a frosted texture that you can see and especially if you can feel it, it's damage reaching to the actual glass, not only to the coating. An expert can remove the coating and repolish the glass surface, but not many people can do this, at prices individuals can afford.

One hears about this more with some lens models than others, I don't really understand the reasons. I don't know if it has to do with particular cements, or reaction of cements to particular glass types. In some lens models, damage seems common on an exterior surface and there the attack-by-lubricants theory may be what's happening (example: Canon rangefinder 50/1.8, I think). But it's still unclear if it's happening to a particular type of glass or is worse under certain storage conditions or what. I don't think it's possible to generalize that all lenses of any given manufacturer or type will develop haze.

There are a number of different optical issues mentioned here, I'll try to clarify some with what I know. For reference, I've only separated a hand full of balsam cemented doublets and reassembled them with optical epoxy, and I've only removed the AR coating on one lens, but I've never re-coated it (as the vacuum evaporation set-up I had was not performing to the level I wanted)

Canadian Balsam is a resin from the North American eastern Fir, the majority of which is in Canada, hence the name. It has good stable optical and adhesive properties, hence it's use. After WW2, there was a move to other optical cements, manufactures tried and rejected many until they settled on optical epoxies & acrylics. For instance, Zeiss had many issues with cemented doublets delamlinating and/or hazing from that time.

Canadian Balsam has good longevity, the Mamiya lens series that have cemented haze issues probably was sourcing other balsam before switching to optical epoxy (I don't have a reference for this, so take it as you may).

Haze in a balsam cemented doublet can come from 2 sources, crystallization of the balsam, or fungus growth in the balsam. Crystalization is rare with good filtered Canadian Balsam. But if it happens with balsam, heating the doublet until the balsam softens and re-amorphousizes will clear it. With fungus, you should separate the doublet, clean, and re-cement (with either balsam or epoxy). Separation can be done with heat or solvent (Xylene).

Some doped optical glass can oxidize from moisture and oxygen, leaving a white milky etched surface. These are usually protected by a hard AR coating to prevent this, and sealed inside an optical group (which you can only access by cutting it open). Sometimes the AR coating is insufficient (ie: Minolta M 2.8/28), or it gets damaged. This happens pretty rarely, but if the optical surface feels textured, it's probably the case. Even if you re-polish these, the oxidization will return unless you re-coat/re-seal the surface.

Otherwise haze on the inner lens surface is either dust or some liquid evaporate from the lubrication used, which can usually be mechanically cleaned off.

I have 3 K/L lenses, more than 10 years, none show any signs of any issues. But most K/L lenses are now available from Japan and hardly anywhere else. And Japan hazes up a lot of glass no other country seems to, so I would say be careful with evaluation when getting it from that end of the world. One of my RB67s with 75 K/L came from South Korea and that has no issues.