[rollei_list] Re: Rolleiflex Mirrors.
----- Original Message ----- From: "todd belcher" <todd_belcher@xxxxxxxxx> 
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, March 21, 2007 9:14 AM
Subject: [rollei_list] Re: Rolleiflex Mirrors.
Many people say they manufacture these mirrors to Rollei specs, but they do not know what they are really talking about. The 'hard' part of manufacturing these mirrors to spec is that they are vacuum coated with the same anti-reflection material that is on lenses. This 
prevents the front surface mirror material from tarnishing.

todd
I suspect the mirror coatings are actually slightly different but on the same line. Mirror coatings can be made to increase the reflectivity of the mirror material was well as providing considerable protection to the mirror. Graphs in standard optics handbooks show the results of such coatings which can improve the overall efficiency of an aluminum mirror to that of silver. Coating of either lenses or mirrors is not trivial. There is a good deal of general information about vacuum coating at the Society of Vacuum Coaters site: http://www.svc.org Click on "History" for some very intresting publications. 

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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