Mysterious Haze on Nikkor HC 50mm F/2 LTM lens

[RussPhoto]

Hello Everyone!

I took out for cleaning rear triplet glass of 50mm Nikkor HC F/2 LTM thinking it was hazy because of internal lubricant fumes. Surprisingly, after two weeks the haze returned! I dismantled it again and cleaned it a second time, checked it in about two weeks and it was hazy again… Now this rear glass triplet glass sits outside of the lens in a lens tissue and every two weeks I have to clean the haze again and again... I tried Zeiss lens fluid and Ronsonol but it didn't help... Any idea what could be that and how to get rid of that haze. I’ve heard that the coating of the lens glass might emit some gas causing that haze? This is a concave lens part facing aperture blades I have a problem with. Thank you!

 

[peterm1]

Superficially it does sound to me like outgassing from the lube. I have the same lens - I must check it as I have not used it for a while now but I cannot recall experiencing it myself with this lens specifically. I have heard of lenses that repeatedly become hazed in this manner, but never quite so quickly. One I know of and own is the Canon 50mm f1.2 LTM lens. A famous lens but also one that is known to be prone to repeated hazing and perhaps every year or so it is necessary to strip the offending elements out and clean them. Fortunately, the lens is very easy to open up and clean in this manner. It is reputedly due to outgassing and if so it could potentially be solved by stripping down the helicoids, cleaning them and relubing with a modern lubricant which is not prone to outgassing. I have never bothered as I hate working with helicoids and a once a year clean is no big issue for me. But if this is confirmed to be the source of your issue the same fix may be needed.

There is the possibility of something that occurs to me as a means of managing the issue though. Hazing from outgassing is more of an issue I believe if the lens is subject to even small amounts of moisture and or heat. Warmth increases outgassing and moisture increases its effects on the elements. Indeed when buying lenses from Japan I have learned to be ultra careful about the number of lenses with haze. This is a special problem in that country where most of it is subject to hot and humid summers. After your next clean try putting the lens in a plastic container with a bag of silica gel or similar desiccant and try to make sure it is stored in a place where the temperature is stable and not too warm. I am not saying these are the issues causing your problem but they do occur to me to be things I would try first in your situation.

 

[dexdog]

That is an odd one, normally the haze is due to lubricants inside the optical block, as you and peterm1 have stated. Given that the lens coating is a vaporized metal compound, I would think that outgassing would not be an issue with the coating itself. My guess is that the coating is oxidizing, given that you can clean it but the issue returns even when the glass is nowhere near old lubricants. Perhaps the coating on the rear doublet was damaged by lubricants in the past that has degraded the coating enough that it oxidizes readily. Lotsa things can happen to 60 to 70 year old lenses. Sounds like a case for Sonnar Brian.

 

[RussPhoto]

Superficially it does sound to me like outgassing from the lube. I have the same lens - I must check it as I have not used it for a while now but I cannot recall experiencing it myself with this lens specifically. I have heard of lenses that repeatedly become hazed in this manner, but never quite so quickly. One I know of and own is the Canon 50mm f1.2 LTM lens. A famous lens but also one that is known to be prone to repeated hazing and perhaps every year or so it is necessary to strip the offending elements out and clean them. Fortunately, the lens is very easy to open up and clean in this manner. It is reputedly due to outgassing and if so it could potentially be solved by stripping down the helicoids, cleaning them and relubing with a modern lubricant which is not prone to outgassing. I have never bothered as I hate working with helicoids and a once a year clean is no big issue for me. But if this is confirmed to be the source of your issue the same fix may be needed.

There is the possibility of something that occurs to me as a means of managing the issue though. Hazing from outgassing is more of an issue I believe if the lens is subject to even small amounts of moisture and or heat. Warmth increases outgassing and moisture increases its effects on the elements. Indeed when buying lenses from Japan I have learned to be ultra careful about the number of lenses with haze. This is a special problem in that country where most of it is subject to hot and humid summers. After your next clean try putting the lens in a plastic container with a bag of silica gel or similar desiccant and try to make sure it is stored in a place where the temperature is stable and not too warm. I am not saying these are the issues causing your problem but they do occur to me to be things I would try first in your situation.

It has been sitting in a plastic bag wrapped in Kimtech tissue for about two month among my other lenses. Haze appears only from one side of the triplet, a sort of stain haze spot visible only on the surface of the glass, the other side of the triplet is crystal clear. Definitely, the problem is only on one side. Not really a big deal... Could be cleaned easily, just curious what it is? I let it sit for another few month, see what happens... who knows may all gas will be exhausted one day😄

 

[RussPhoto]

That is an odd one, normally the haze is due to lubricants inside the optical block, as you and peterm1 have stated. Given that the lens coating is a vaporized metal compound, I would think that outgassing would not be an issue with the coating itself. My guess is that the coating is oxidizing, given that you can clean it but the issue returns even when the glass is nowhere near old lubricants. Perhaps the coating on the rear doublet was damaged by lubricants in the past that has degraded the coating enough that it oxidizes readily. Lotsa things can happen to 60 to 70 year old lenses. Sounds like a case for Sonnar Brian.

The other side of the triplet is crystal clear, the lens itself was very clean when I received it, no oil stains on aperture blades, very clean lens. Definitely, some outgassing. I don't see any damage on coating also, when it cleaned it look absolutely clear but after some time all comes back again.

 

[peterm1]

It has been sitting in a plastic bag wrapped in Kimtech tissue for about two month among my other lenses. Haze appears only from one side of the triplet, a sort of stain haze spot visible only on the surface of the glass, the other side of the triplet is crystal clear. Definitely, the problem is only on one side. Not really a big deal... Could be cleaned easily, just curious what it is? I let it sit for another few month, see what happens... who knows may all gas will be exhausted one day😄

".............................who knows may all gas will be exhausted one day😄" My wife keeps hoping that about me. So far, she has been disappointed. 😆

 

[dexdog]

The other side of the triplet is crystal clear, the lens itself was very clean when I received it, no oil stains on aperture blades, very clean lens. Definitely, some outgassing. I don't see any damage on coating also, when it cleaned it look absolutely clear but after some time all comes back again.

In general, I would expect outgassing to affect all exposed surfaces of the lens group, instead of only one surface, especially if the glass is in a plastic bag and has been removed from the optical block fixture. Why would outgassing only affect the lens surface that was originally closest to the aperture, but not the rear of the same lens group?

 

[RussPhoto]

In general, I would expect outgassing to affect all exposed surfaces of the lens group, instead of only one surface, especially if the glass is in a plastic bag and has been removed from the optical block fixture. Why would outgassing only affect the lens surface that was originally closest to the aperture, but not the rear of the same lens group?

Hard to say...My guess it's only one piece of glass out of three has this problem, it appears like a stain spot which could be only seen under the angle when shining strong light, easy to clean with just a few wipe