Canon LTM Serenar/Canon 28 f3.5 comparison?

[charjohncarter]

That's a common misconception with Canon LTM lenses. You could completely relube the lens with modern grease and you'd still get haze. Thats because the cause of the haze is the type of glass used in the element that hazes up. I have no idea what Canon added to the glass used in that element to achieve the desired refractive index, but it must be pretty dodgy stuff.

I guess it doesn't really matter (glass coat or oil) as long as you don't get one of these and/or you are willing clean it every few months. Even though I like my lens, I don't like to clean it.

Strangely, I have a 100mm Serenar from the same period and it has always been clear. So probably you are right about the glass coating.

 

[jonmanjiro]

I guess it doesn't really matter (glass coat or oil) as long as you don't get one of these and/or you are willing clean it every few months. Even though I like my lens, I don't like to clean it. Strangely, I have a 100mm Serenar from the same period and it has always been clear. So probably you are right about the glass coating.

It's not the coating, it's the actual glass used. Glass makers use all sorts of additives to achieve the required refractive indexes of the elements in a lens. Sometimes the additives are radioactive or poisonous, or both. Whatever Canon used in some of its LTM lenses causes the glass to haze.

Yamazaki-San of Yamazaki Optics, a well known lens repolishing and recoating service in Tokyo, explained it to me when I asked about getting some Canon lenses cleaned one time. He told me not waste my money as the haze will just occur again.

 

[charjohncarter]

It's not the coating, it's the actual glass used. Glass makers use all sorts of additives to achieve the required refractive indexes of the elements in a lens. Sometimes the additives are radioactive or poisonous, or both. Whatever Canon used in some of its LTM lenses causes the glass to haze.

Yamazaki-San of Yamazaki Optics, a well known lens repolishing and recoating service in Tokyo, explained it to me when I asked about getting some Canon lenses cleaned one time. He told me not waste my money as the haze will just occur again.

Thanks for the explanation, but really to the OPs point, about changing his lenses for some perceived optical quality increase is nuts. There are more important reason to not switch a lens. If he is reasonably happy with present lenses, just be damn sure you don't get one that may have a little better optics but needs to be cleaned every fortnight.

 

[jonmanjiro]

It's not the coating, it's the actual glass used. Glass makers use all sorts of additives to achieve the required refractive indexes of the elements in a lens. Sometimes the additives are radioactive or poisonous, or both. Whatever Canon used in some of its LTM lenses causes the glass to haze.

Yamazaki-San of Yamazaki Optics, a well known lens repolishing and recoating service in Tokyo, explained it to me when I asked about getting some Canon lenses cleaned one time. He told me not waste my money as the haze will just occur again.

Just stumbled on the very interesting quote below on the head bartender's website (link here - scroll down the the "Fogging" section). Other than the fact that Mr. Braun doesn't seem to know about the Canon LTM lenses that are prone to haze, it confirms what Yamazaki-San of Yamazaki Optics says.

Leitz chrome lenses from the 50's and early 60's are very prone to "fogging" or "hazing."

For years I accepted the story it was due to the whale oil lubricants used at the time. It made a lot of sense to me since something was in there fogging the lenses....how could it be the metal or glass?? Alas, logic does not always work when it comes to Leica. Extensive discussions with Mr. Horst Braun, the Manager of the Leica repair department have proven otherwise. He states:

"the special glasses with high refractive index which were used, where unfortunately prone to corrosive damage due to the glass components absorption of moisture. Only later with the availability of new anti-reflective coatings was it possible to eliminate this problem. I still do not believe, that lubricants should be the cause for fogging, because also some internal lenses where affected which never could possibly come into contact with lubricants. I suspect, that the reason why Nikon and Canon did not have this problem at the time was probably due to the fact that they used less sensitive glasses in their objectives."