Archived posting to the Leica Users Group, 2003/07/30

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Subject: [Leica] Crazing Explanation
Date: Wed, 30 Jul 2003 20:19:16 -0400


Crazing usually refers to the breakdown or failure of the anti-
reflective layer coating.  It can look like a series of hairline cracks 
on the surface of a lens.  It is acutally the layer on top of the lens 
put there to enhance light transmission.  This breakdown can 
occur over time and can be accelerated with exposure to some 
cleaning agents, extreme temperature shifts and general physical 
abuse.  The newer antireflective coatings for camera lenses as 
well as spectacle lenses can be 9 layers or more including a few 
SiO2 (silica dioxide) layers - otherwise known as qaurtz to 
enhance scratch resistance.  If the crazing covers enough of the 
surface area of the front element, it will lower contrast of the image.  
I have heard of technicians that can clean the surface and re-coat.  
I have nevere seen such a lens after treatment but it is technically 
possibel to do so if the lens suface is intact.  Perhaps someone on 
the list knows the camera technician who polishes and re-coats 
lens elements.

Richard Clompus, OD
Roanoke, VA     

> Is crazing repairable?
> Robert VanLane

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