What causes "light hazing" ?

[ECohen]

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I've been looking at used lenses........And was surprised how often a Leica ad reads "light haze"
What causes a "light haze" in 10 to15 year old lenses?  Why would a fairly new  lens experience hazing?

Did the original owner of these lenses do something wrong?

 

I use my cameras daily so I don't think about storing them.
 

opinions and thoughts welcome and appreciated

[jdlaing]

One cause is heat gassing off the lubricants and the vapor sticking to the glass elements inside the lens.

[spydrxx]

More lens sellers are paying closer attention to accurate descriptions of their wares, as are buyers, so to CYA many sellers are describing "light hazing" which would have gone unnoticed 5-10 years ago. Essentially it is easy to diagnose, shining a flashlight thru the lens usually reveals all sort of interesting issues like light dust and hazing. Much of it is virtually insignificant for 95% of the users, but for perfectionists paying Leica prices, nothing goes unnoticed. The main cause of light hazing is as jdlaing cited above, but it can also come about by the normal "breathing" of lenses as they are focussed, especially in heavily polluted areas (think Asian cities, LA, etc) as well as heavy use near seashores....moisture drawn in and evaporating leaving pollutants.

[ECohen]

So its not caused by poor storage or abuse ?

 

It could begin by simply hiking a hot desert or shooting regularly in polluted cities ?

Interesting ....thanks for the education.

[pgk]

Some glass types can oxidise especially if they get wet (condensation). I've seen this on underwater camera ports made from 'mineral' glass and it occurs when they are left wet or have a neoprene cover fitted when wet and not dried properly. Under such circumstances the port can exhibit 'hazing' within a few years. Solution is to dry it thoroughly after use - with camera lenses changes in humidity or temperature may result in condensation which could well cause hazing too. So prevention of condensation is a preferable way of using lenses though its not alway possible. With modern coatings this should be much less of a problem though I suppose it depends on the coating and its resilience to chemical shifts or oxidation if condensation occurs.

[jdlaing]

Yes on both poor storage and abuse as well as neglect.